We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-...We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.展开更多
After a two-year-long investigation and considerable research, CAS (Chinese Academy of Sciences) recently defined its long-term and medium strategic targets for the development of high-energy physics and advanced acce...After a two-year-long investigation and considerable research, CAS (Chinese Academy of Sciences) recently defined its long-term and medium strategic targets for the development of high-energy physics and advanced accelerator facilities: ·Making a major renovation on the Beijing Electron-Positron Collider (BEPC) so that it is capable of accomplishing top-ranking research results in charmphysics;展开更多
Charge strippers play an essential role in heavy-ion accelerators by stripping the projectile ions to higher charge states to enhance the acceleration efficiency downstream of the stripper.In the high-energy mode of t...Charge strippers play an essential role in heavy-ion accelerators by stripping the projectile ions to higher charge states to enhance the acceleration efficiency downstream of the stripper.In the high-energy mode of the booster ring(BRing)of the high-intensity heavy-ion accelerator facility,the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing.The key parameters of the stripper and stripped ions were calculated,and the influence of stripping on the beam quality was discussed.To get high stripping efficiencies,the foil thicknesses and resultant charge state distributions for the typical ions were determined by the code ETACHA.The equilibrium thickness was obtained for the U beam,while the stripper thicknesses for the Xe and Kr beams were determined based on a compromise between the stripped charge states and the stripping efficiency.The energy loss,energy straggling,and emittance growth due to stripping have a non-negligible impact on the transport of the stripped beams and the injection of the ring.Therefore,these parameters were simulated by GEANT4.In addition,the foil’s temperature evolution,which greatly affects the foil lifetime,was simulated by ANSYS.The maximum temperature of the foil bombarded by the U and Xe beams with the nominal parameters will exceed the safe value in terms of the impact of evaporation on the foil’s lifetime.Given the foil temperature constraint,the highest tolerable beam intensity and the injected ion number into the ring were derived for different beam sizes.The results of this paper will present important reference data for the optimization design and commissioning of the beamline and injection to the BRing for the stripped ions.展开更多
This study was to compare theoretical calculation and practical measurement structure response of asphalt pavement. Analysis of the pavement layer moduli was determined from a Back-calculation of Falling Weight Deflec...This study was to compare theoretical calculation and practical measurement structure response of asphalt pavement. Analysis of the pavement layer moduli was determined from a Back-calculation of Falling Weight Deflectometer (FWD) data and the measured stiffness moduli of asphalt layer cores. The pavement response was calculated using a theoretical model and the measured strain response at the bottom different layers. Layered elastic theory was used to back-calculate the layer moduli and three different theory models were used to forward calculate the strain and deflection. The models were: Layered Elastic Theory (LET), the Method of Equivalent Thicknesses (MET) with linear elastic and the Finite Element Method (FEM) where asphalt layer may be viscoelastic. The results showed that the calculation structure response from FEM was consistent with measured results.展开更多
This study investigates the influence of seismic activities on the optical synchronization system of the European X-ray Free-Electron Laser.We analyze the controller input/output data of phase-locked loops in length-s...This study investigates the influence of seismic activities on the optical synchronization system of the European X-ray Free-Electron Laser.We analyze the controller input/output data of phase-locked loops in length-stabilized links,focusing on the response to earthquakes,ocean-generated microseism and civilization noise.By comparing the controller data with external data,we were able to identify disturbances and their effects on the control signals.Our results show that seismic events influence the stability of the phase-locked loops.Even earthquakes that are approximately 5000 km away cause remarkable fluctuations in the in-loop control signals.Ocean-generated microseism in particular has an enormous influence on the in-loop control signals due to its constant presence.The optical synchronization system is so highly sensitive that it can even identify vibrations caused by civilization,such as road traffic or major events like concerts or sport events.The phase-locked loops manage to eliminate more than 99%of the existing interference.展开更多
This paper presents a detailed technical overview of the femtosecond precision timing and synchronization systems implemented at the Shanghai high repetition rate XFEL and extreme light facility(SHINE).These systems a...This paper presents a detailed technical overview of the femtosecond precision timing and synchronization systems implemented at the Shanghai high repetition rate XFEL and extreme light facility(SHINE).These systems are designed to deliver stabilized optical references to multiple receiver clients,ensuring high-precision synchronization between the optical master oscillator(OMO)and optical/RF subsystems.The core components include an OMO,fiber length stabilizers and laser-to-laser synchronization modules that achieve femtosecond-level accuracy.Our discussion extends to the various subsystems that comprise the synchronization infrastructure,including the OMO,fiber length stabilizer and advanced phase detection techniques.Finally,we highlight ongoing research and development efforts aimed at enhancing the functionality and efficiency of these systems,thereby contributing to the advancement of X-ray freeelectron laser technology and its applications in scientific research.展开更多
Research activities of nuclear physics at Radioactive Isotope Beam Factory over 10 years are reviewed and future directions are also discussed. Conceptual ideas in designing the facility as well as experimental device...Research activities of nuclear physics at Radioactive Isotope Beam Factory over 10 years are reviewed and future directions are also discussed. Conceptual ideas in designing the facility as well as experimental devices are introduced. Special emphasis is given to highlighted results obtained at RIBF.展开更多
基金supported in part by the National Key R&D Program of China (Contract Nos.2023YFA1606500,2024YFE0109800,and 2024YFE0110400)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34010000)+5 种基金the Gansu Key Project of Science and Technology (Grant No.23ZDGA014)the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2021B0301030006)the National Natural Science Foundation of China (Grant Nos.12105328,W2412040,12475126,12422507,12035011,12375118,12435008,and W2412043)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-002)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant Nos.2020409 and 2023439)the Russian Science Foundation (Grant No.25-42-00003)。
文摘We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.
文摘After a two-year-long investigation and considerable research, CAS (Chinese Academy of Sciences) recently defined its long-term and medium strategic targets for the development of high-energy physics and advanced accelerator facilities: ·Making a major renovation on the Beijing Electron-Positron Collider (BEPC) so that it is capable of accomplishing top-ranking research results in charmphysics;
文摘Charge strippers play an essential role in heavy-ion accelerators by stripping the projectile ions to higher charge states to enhance the acceleration efficiency downstream of the stripper.In the high-energy mode of the booster ring(BRing)of the high-intensity heavy-ion accelerator facility,the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing.The key parameters of the stripper and stripped ions were calculated,and the influence of stripping on the beam quality was discussed.To get high stripping efficiencies,the foil thicknesses and resultant charge state distributions for the typical ions were determined by the code ETACHA.The equilibrium thickness was obtained for the U beam,while the stripper thicknesses for the Xe and Kr beams were determined based on a compromise between the stripped charge states and the stripping efficiency.The energy loss,energy straggling,and emittance growth due to stripping have a non-negligible impact on the transport of the stripped beams and the injection of the ring.Therefore,these parameters were simulated by GEANT4.In addition,the foil’s temperature evolution,which greatly affects the foil lifetime,was simulated by ANSYS.The maximum temperature of the foil bombarded by the U and Xe beams with the nominal parameters will exceed the safe value in terms of the impact of evaporation on the foil’s lifetime.Given the foil temperature constraint,the highest tolerable beam intensity and the injected ion number into the ring were derived for different beam sizes.The results of this paper will present important reference data for the optimization design and commissioning of the beamline and injection to the BRing for the stripped ions.
基金Sponsored by the Program of the Highway Department of Ministry of Communications of China (Grant No 2004 318 000 04)
文摘This study was to compare theoretical calculation and practical measurement structure response of asphalt pavement. Analysis of the pavement layer moduli was determined from a Back-calculation of Falling Weight Deflectometer (FWD) data and the measured stiffness moduli of asphalt layer cores. The pavement response was calculated using a theoretical model and the measured strain response at the bottom different layers. Layered elastic theory was used to back-calculate the layer moduli and three different theory models were used to forward calculate the strain and deflection. The models were: Layered Elastic Theory (LET), the Method of Equivalent Thicknesses (MET) with linear elastic and the Finite Element Method (FEM) where asphalt layer may be viscoelastic. The results showed that the calculation structure response from FEM was consistent with measured results.
基金support by DASHH(Data Science in Hamburg-Helmholtz Graduate School for the Structure of Matter)with grant No.HIDSS-0002。
文摘This study investigates the influence of seismic activities on the optical synchronization system of the European X-ray Free-Electron Laser.We analyze the controller input/output data of phase-locked loops in length-stabilized links,focusing on the response to earthquakes,ocean-generated microseism and civilization noise.By comparing the controller data with external data,we were able to identify disturbances and their effects on the control signals.Our results show that seismic events influence the stability of the phase-locked loops.Even earthquakes that are approximately 5000 km away cause remarkable fluctuations in the in-loop control signals.Ocean-generated microseism in particular has an enormous influence on the in-loop control signals due to its constant presence.The optical synchronization system is so highly sensitive that it can even identify vibrations caused by civilization,such as road traffic or major events like concerts or sport events.The phase-locked loops manage to eliminate more than 99%of the existing interference.
基金supported by the National Natural Science Foundation of China(Nos.12105348 and 12275341)the SHINE project(National Major Scientific and Technological Infrastructure,No.NDRC[2017]825).
文摘This paper presents a detailed technical overview of the femtosecond precision timing and synchronization systems implemented at the Shanghai high repetition rate XFEL and extreme light facility(SHINE).These systems are designed to deliver stabilized optical references to multiple receiver clients,ensuring high-precision synchronization between the optical master oscillator(OMO)and optical/RF subsystems.The core components include an OMO,fiber length stabilizers and laser-to-laser synchronization modules that achieve femtosecond-level accuracy.Our discussion extends to the various subsystems that comprise the synchronization infrastructure,including the OMO,fiber length stabilizer and advanced phase detection techniques.Finally,we highlight ongoing research and development efforts aimed at enhancing the functionality and efficiency of these systems,thereby contributing to the advancement of X-ray freeelectron laser technology and its applications in scientific research.
文摘Research activities of nuclear physics at Radioactive Isotope Beam Factory over 10 years are reviewed and future directions are also discussed. Conceptual ideas in designing the facility as well as experimental devices are introduced. Special emphasis is given to highlighted results obtained at RIBF.
