Using two infrared pulsed lasers systems,a picosecond solid-state Nd:YAG laser with tuneable repetition rate(400 kHz-1 MHz)working in the burst mode of a multi-pulse train and a femtosecond Ti:sapphire laser amplifier...Using two infrared pulsed lasers systems,a picosecond solid-state Nd:YAG laser with tuneable repetition rate(400 kHz-1 MHz)working in the burst mode of a multi-pulse train and a femtosecond Ti:sapphire laser amplifier with tuneable pulse duration in the range of tens of femtoseconds up to tens of picoseconds,working in single-shot mode(TEWALASS facility from CETAL-NILPRP),we have investigated the optimal laser parameters for kinetic energy transfer to a titanium target for laser-thrust applications.In the single-pulse regime,we controlled the power density by changing both the duration and pulse energy.In the multi-pulse regime,the train’s number of pulses(burst length)and the pulse energy variation were investigated.Heat propagation and photon reflection-based models were used to simulate the obtained experimental results.In the single-pulse regime,optimal kinetic energy transfer was obtained for power densities of about 500 times the ablation threshold corresponding to the specific laser pulse duration.In multi-pulse regimes,the optimal number of pulses per train increases with the train frequency and decreases with the pulse power density.An ideal energy transfer efficiency resulting from our experiments and simulations is close to about 0.0015%.展开更多
Detecting the X-ray emission of pulsars and obtaining the photons＇ time of arrival are the foundational steps in autonomous navigation via X-ray pulsar measurement.The precision of a pulse＇s time of arrival is mainl...Detecting the X-ray emission of pulsars and obtaining the photons＇ time of arrival are the foundational steps in autonomous navigation via X-ray pulsar measurement.The precision of a pulse＇s time of arrival is mainly determined by the precision of photon arrival time measurement.In this work,a silicon drift detector is used to measure photon energy and arrival time.The measurement system consists of a signal detector,a processing unit,a signal acquisition unit and a data receiving unit.This system acquires the energy resolution and arrival time information of photons.In particular,background noise with different energies disturbs pulse profile forming,the system can also achieve a high signal-to-noise ratio profile.Ground test results show that this system can be applied in autonomous navigation based on X-ray pulsar measurement.展开更多
By virtue of the generalised Hermann-Feynmam theorem we re-derive the energy average formula of photon gas. This is another useful application of the theorem.
The high-energy photon source(HEPS)is the first fourth-generation synchrotron light source facility in China.The HEPS injector consists of a linear accelerator(Linac)and a full energy booster.The booster captures the ...The high-energy photon source(HEPS)is the first fourth-generation synchrotron light source facility in China.The HEPS injector consists of a linear accelerator(Linac)and a full energy booster.The booster captures the electron beam from the Linac and increases its energy to the value required for the storage ring.The full-energy beam could be injected to the storage ring directly or after“high-energy accumulation.”On November 17,2023,the key booster parameters successfully reached their corresponding target values.These milestone results were achieved based on numerous contributions,including nearly a decade of physical design,years of equipment development and installation,and months of beam commissioning.As measured at the extraction energy of 6 GeV,the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm rad with a single-bunch charge of 5.58 nC,compared with the corresponding target values of 6.6 mA and 35 nm rad,respectively.This paper presents the physical design,equipment development,installation,and commissioning process of the HEPS booster.展开更多
The Ionising irradiations used mostly in the treatment of tumoral diseasses are: X, γ, β and e irradiations. The discussion will be about γ irradiations, produced in linear accelerator with photon energy 6 MV and 1...The Ionising irradiations used mostly in the treatment of tumoral diseasses are: X, γ, β and e irradiations. The discussion will be about γ irradiations, produced in linear accelerator with photon energy 6 MV and 15 MV. It is important to know the absorption performance before and after the electronic equilibrium. This is a reason that we’ve used the function of dose gradient for irradiations γ. It represents the velocity of dose change as a function of depth in tissue. From skin to maximum dose value, the increase of G-function is more accentuated for γ-rays than for β-particles while after that the G-function decreasing is less sharp for γ-rays. Finally, we’ll discuss about the advantages in terms of radiation protection of γ-rays used in radiotherapy.展开更多
This paper begins by exploring a useful and neglected detail of a photon—its physical size perpendicular to the direction of propagation in the same way as an atom or neutron has a physical size. Such a photon size w...This paper begins by exploring a useful and neglected detail of a photon—its physical size perpendicular to the direction of propagation in the same way as an atom or neutron has a physical size. Such a photon size would be quite separate from the cross-section of a photonic interaction, which depends on the material interacting. Such a perpendicular dimension of a photon will be invariant under Lorentz transform parallel to the light propagation direction and will thus be the same for all frequencies of light. This study also leads to new details about how a photon interacts, offering an explanation for the familiar physics where light slightly above and below the mean frequency of an excited state can still excite the same state without violation of conservation of energy—a mystery explored thoroughly in a previous paper without finding the solution offered here. As usual, a better elucidation of the details of light interaction also leads to new insights—especially about the vacuum field. The <strong>Appendix </strong>summarizes some previous research relevant to this展开更多
Many properties of a single photon, such as density, rest mass, and orbital angular momentum, are still unknown. In a previous study, the photon was presented as a superfluid prolate spheroid structure, with a long-ax...Many properties of a single photon, such as density, rest mass, and orbital angular momentum, are still unknown. In a previous study, the photon was presented as a superfluid prolate spheroid structure, with a long-axis radius, short-axis radius, and volume, embodied with two spins—transversal and longitudinal—which are responsible for the three-dimensional helical trajectory of the electromagnetic wave. In this study, the rest mass, density, and energy of photon are mathematically derived, and the relationship between the radius of photon and its frequency is demonstrated. In addition, the difference between the Compton and de Broglie wavelengths is clarified. The calculated density, volume, and rest mass of photon agree with previous experimental results. The photon’s simultaneous longitudinal and transversal spins are moving forces of longitudinal and transversal trajectories, which are the origin of the three-dimensional helix shape of the electromagnetic field. A new mechanism for the photon movement is proposed, and the reason for the zero mass moving photon is revealed;a traveling photon in space exhibits zero mass because its boundaries demonstrate zero relative velocity with the surrounding vacuum. The orbital angular momentum of photon is described using similar macroscopic rotation concepts and applying hydrodynamics laws. A rotating photon is endowed with an angular velocity vector whose magnitude measures the speed with which the radius of the principal axis sweeps an angle, and whose direction indicates the principal axis of rotation and is given by the right-hand rule. The deviation angle is calculated using trigonometric functions, and the origin of the Lorenz factor is revealed.展开更多
Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to acc...Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to accommodate the accelerator physics design.Superconducting rf(srf)technologies were chosen for the storage ring rf accompanied by solid-state power amplifiers and digital low-level rf controls.The design of the rf system was completed,and the parameters are frozen.Elucidation of the rf design with key parameters is desired.Methods The requirements from the accelerator physics design will be presented followed by the detailed rf design.The logic behind the choice of key rf parameters is elaborated.The configuration of the entire rf system is presented.Results and conclusions The fundamental srf cavity of 166.6 MHz was designed to accelerate the ultrarelativistic electron beam.Heavy damping of higher-order modes in these cavities is required to avoid the coupled bunch instabilities.An active third harmonic srf of 499.8 MHz was adopted to realize the required rf gymnastics.Normal-conducting 5-cell cavities will be used for the booster rf.Solid-state amplifiers of 2.4 MW in total will be installed at HEPS to drive these cavities in the booster and the storage ring.A digital low-level rf system will be used to regulate rf field inside each cavity with high stabilities.The rf configuration during the commissioning and the operation scenarios are also presented.展开更多
Purpose The physics design of the High Energy Photon Source(HEPS)was finished after many times of iteration.Hereby,the typical equilibrium electron beam parameters corresponding to the proposed two baseline operation ...Purpose The physics design of the High Energy Photon Source(HEPS)was finished after many times of iteration.Hereby,the typical equilibrium electron beam parameters corresponding to the proposed two baseline operation modes in the baseline design of HEPS are presented.Methods To compute the equilibrium parameters of the electron beam,the lattice parameters,RF parameters,and the parameters of the insertion devices(IDs)were determined first.Furthermore,it is more precise to use the full-current electron beam parameters in the estimations of the performance of the synchrotron light.Therefore,not only the single-particle dynamics but also the current-dependent collective effects need to be considered in the computations of the full-current,equilibrium parameters of the electron beam.Both analytic computations and multi-particle tracking simulations were carried out.Results The full-current,equilibrium parameters of the electron beams in the HEPS storage ring are presented in this paper.Moreover,the main beam parameters in the injector(the booster and the LINAC),corresponding to the two baseline operation modes of the storage ring,are also presented.Conclusion The typical electron beam parameters corresponding to the two baseline operation modes are given in detail in this paper.展开更多
The optical conductivity of a trilayer graphene is studied using the Kubo-Greenwood formula. We calculate the real part of the diagonal optical conductivity of an ABA-stacked trilayer graphene with different Fermi ene...The optical conductivity of a trilayer graphene is studied using the Kubo-Greenwood formula. We calculate the real part of the diagonal optical conductivity of an ABA-stacked trilayer graphene with different Fermi energies. The optical conductivity arises from interband matrix elements of the electric current operator involving the transitions from the occupied states to the unoccupied ones. We study the dependence of the real part of the diagonal optical conductivity on the photon energy, and the role of the transitions.展开更多
We combine the de Broglie Matter Wave Equation with the Heisenberg Uncertainty Principle to derive an equation for time as a wave. This happens to be the first time that these two statements have been combined in this...We combine the de Broglie Matter Wave Equation with the Heisenberg Uncertainty Principle to derive an equation for time as a wave. This happens to be the first time that these two statements have been combined in this manner to derive an equation for time. The result is astounding. Time turns out to be a minuscule blob of quantum electromagnetic energy in perpetual angular momentum. From this time equation, we derive an equation for space which turns out to also predict a string (like the string of string theory). We then combine the time equation with the space equation to derive an equation for the inverse of quantum gravity which is also surprisingly electromagnetic in nature. This last statement implies that space is multidimensional and gravity in multidimensional space is not quantized, but its inverse (which is single-dimensional) is.展开更多
Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically...Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.展开更多
At the High Energy Photon Source (HEPS),a high orbital stability of typically 10% of the beam size and angular divergence must be achieved.The beam size at the insertion devices is 10μm horizontally and 1μm vertical...At the High Energy Photon Source (HEPS),a high orbital stability of typically 10% of the beam size and angular divergence must be achieved.The beam size at the insertion devices is 10μm horizontally and 1μm vertically,which implies that the beam orbit must be stabilized to the sub-micrometer level.This results in stringent tolerance and quality control requirements for the series production of beam position monitor (BPM) pickups.In this study,analytical formulas were used and CST simulations were performed to analyze the effects of the mechanical tolerances of BPM pickups on beam position measurement.The results of electromagnetic?eld simulations revealed how various mechanical errors,such as button size and location accuracy,as well as the related button capacitance,exert different in?uences on the beam position measurement.The performance of an actual BPM pickup was measured,along with an assessment of the error on the beam position measurement.Additionally,a wake?eld analysis,including an investigation of trapped resonant modes and related thermal deformation,was conducted.展开更多
We review current silicon photonic devices and their performance in connection with energy consumption.Four critical issues are identified to lower energy consumption in devices and systems: reducing the influence of ...We review current silicon photonic devices and their performance in connection with energy consumption.Four critical issues are identified to lower energy consumption in devices and systems: reducing the influence of the thermo-optic effect, increasing the wall-plug efficiency of lasers on silicon, optimizing energy performance of modulators, and enhancing the sensitivity of photodetectors. Major conclusions are(1) Mach–Zehnder interferometer-based devices can achieve athermal performance without any extra energy consumption while microrings do not have an efficient passive athermal solution;(2) while direct bonded III–V-based Si lasers can meet system power requirement for now, hetero-epitaxial grown III–V quantum dot lasers are competitive and may be a better option for the future;(3) resonant modulators, especially coupling modulators, are promising for low-energy consumption operation even when the power to stabilize their operation is included;(4) benefiting from high sensitivity and low cost, Ge/Si avalanche photodiode is the most promising photodetector and can be used to effectively reduce the optical link power budget. These analyses and solutions will contribute to further lowering energy consumption to meet aggressive energy demands in future systems.展开更多
To establish a nuclear resonant scattering beamline at the High Energy Photon Source(HEPS),it is essential to develop tools for detection and cleaning of parasitic bunches,for meeting the stringent demands on bunch pu...To establish a nuclear resonant scattering beamline at the High Energy Photon Source(HEPS),it is essential to develop tools for detection and cleaning of parasitic bunches,for meeting the stringent demands on bunch purity.To this end,a novel time-correlated single-photon counting system was implemented at the electron storage ring of the Beijing Electron–Positron Collider II(BEPCII).The purity deterioration process over a week-long operation was recorded by the system.In this study,the mechanism of impurity growth was analyzed by numerical methods and validated on measurements.The agreement between the experimental results and the cal-culation was fairly good.Two main sources of parasitic bunches,pre-accelerators and the Touschek scattering were confirmed.A bunch-cleaning technique,based on a sinu-soidal signal mixed with a pseudo-square wave,was also developed and implemented,and its capability to improve the bunch purity to the level of 10–7 was experimentally demonstrated.We present the experimental setup,princi-ple,and measurement results of a system for detection and cleaning of parasitic bunches.展开更多
A new generation of storage ring-based light sources,called diffraction-limited storage rings（DLSRs）,with emittance approaching the diffraction limit for multi-keV photons by means of multi-bend achromat lattices,ha...A new generation of storage ring-based light sources,called diffraction-limited storage rings（DLSRs）,with emittance approaching the diffraction limit for multi-keV photons by means of multi-bend achromat lattices,has attracted extensive studies worldwide.Among various DLSR proposals,the hybrid multi-bend achromat concept developed at the European Synchrotron Radiation Facility（ESRF） predicts an effective way of minimizing the emittance while keeping the required chromatic sextupole strengths to an achievable level.For the High Energy Photon Source planned to be built in Beijing,an ESRF-type lattice design consisting of 48 hybrid seven-bend achromats is proposed to reach emittance as low as 60 pm-rad with a circumference of about 1296 m.Sufficient dynamic aperture,allowing vertical on-axis injection,and moderate momentum acceptance are achieved simultaneously for a promising ring performance.展开更多
The High Energy Photon Source(HEPS)is a 6 GeV diffraction-limited storage ring light source under construction.The swap-out injection is adopted with the depleted bunch recycled via high-energy accumulation in the boo...The High Energy Photon Source(HEPS)is a 6 GeV diffraction-limited storage ring light source under construction.The swap-out injection is adopted with the depleted bunch recycled via high-energy accumulation in the booster.The extremely high beam energy density of the bunches with an ultra-low emittance(about 30 pm horizontally and 3 pm vertically)and high bunch charges(from 1.33 to 14.4 nC)extracted from the storage ring could cause hazardous damage to the extraction Lambertson magnet in case of extraction kicker failure.To this end,we proposed the use of a pre-kicker to spoil the bunches prior to extraction,significantly reducing the maximum beam energy density down to within a safe region while still maintaining highly efficient extractions.The main parameters of the pre-kicker are simulated and discussed.展开更多
Purpose Based on the requirements of the High Energy Photon Source(HEPS),the key components for strip-type and button-type beam position monitors(BPMs)and feedthroughs are designed and manufactured.Method The mechanic...Purpose Based on the requirements of the High Energy Photon Source(HEPS),the key components for strip-type and button-type beam position monitors(BPMs)and feedthroughs are designed and manufactured.Method The mechanical structure of the feedthroughs is designed according to the Computer Simulation Technology(CST)simulation results.Resultsandconclusions Small batches of feedthroughs are manufactured,and the structure is optimized based on mechanical,vacuum,electromagnetic,and other characteristic test results.The performance improved significantly owing to optimization through batch product testing,and quality control-related information from several manufacturers is obtained,which provide a foundation for the development of BPMs for HEPS.展开更多
The emission of coumarin 6（C-6） doped in opal polymethylmethacrylate（PMMA） photonic crystal（PC） was effectively manipulated. Meanwhile the energy transfer（ET） of C-6 in PCs, which are infiltrated with sulforho...The emission of coumarin 6（C-6） doped in opal polymethylmethacrylate（PMMA） photonic crystal（PC） was effectively manipulated. Meanwhile the energy transfer（ET） of C-6 in PCs, which are infiltrated with sulforho- damine B（S-B）, was influenced by the concentration of energy acceptor in solution, the size of PMMA micro- sphere（SM） and the photonic stop band（PSB）. The results should be beneficial to people to further understand the potential application of PCs in optoelectronic fields.展开更多
During the last few years,active personal dosimeters have been developed and have replaced passive personal dosimeters in some external monitoring systems,frequently using silicon diode detectors.Incident photons inte...During the last few years,active personal dosimeters have been developed and have replaced passive personal dosimeters in some external monitoring systems,frequently using silicon diode detectors.Incident photons interact with the constituents of the diode detector and produce electrons.These photon-induced electrons deposit energy in the detector＇s sensitive region and contribute to the response of diode detectors.To achieve an appropriate photon dosimetry response,the detectors are usually covered by a metallic layer with an optimum thickness.The metallic cover acts as an energy compensating shield.In this paper,a software process is performed for energy compensation.Selective data sampling based on pulse height is used to determine the photon dose equivalent.This method is applied to improve the energy response in photon dosimetry.The detector design is optimized for the response function and determination of the photon dose equivalent.Photon personal dose equivalent is determined in the energy range of 0.3-6 MeV.The error values of the calculated data for this wide energy range and measured data for ^133Ba,^137Cs,^60Co and ^241Am-Be sources respectively are up to 20%and 15%.Fairly good agreement is seen between simulation and dose values obtained from our process and specifications from several photon sources.展开更多
基金supported by the Ministry of Research,Innovation and Digitization(Ministerul Cercetarii,Inovarii si Digitalizarii)/Institute of Atomic Physics from the National Research-Development and Innovation Plan Ⅲ for 2015-2020/Programme 5/Subprograme 5.1 ELI-RO,project ELIRO No ELI_13/16.10.2020.
文摘Using two infrared pulsed lasers systems,a picosecond solid-state Nd:YAG laser with tuneable repetition rate(400 kHz-1 MHz)working in the burst mode of a multi-pulse train and a femtosecond Ti:sapphire laser amplifier with tuneable pulse duration in the range of tens of femtoseconds up to tens of picoseconds,working in single-shot mode(TEWALASS facility from CETAL-NILPRP),we have investigated the optimal laser parameters for kinetic energy transfer to a titanium target for laser-thrust applications.In the single-pulse regime,we controlled the power density by changing both the duration and pulse energy.In the multi-pulse regime,the train’s number of pulses(burst length)and the pulse energy variation were investigated.Heat propagation and photon reflection-based models were used to simulate the obtained experimental results.In the single-pulse regime,optimal kinetic energy transfer was obtained for power densities of about 500 times the ablation threshold corresponding to the specific laser pulse duration.In multi-pulse regimes,the optimal number of pulses per train increases with the train frequency and decreases with the pulse power density.An ideal energy transfer efficiency resulting from our experiments and simulations is close to about 0.0015%.
基金Supported by National Natural Science Foundation of China(10973048)
文摘Detecting the X-ray emission of pulsars and obtaining the photons＇ time of arrival are the foundational steps in autonomous navigation via X-ray pulsar measurement.The precision of a pulse＇s time of arrival is mainly determined by the precision of photon arrival time measurement.In this work,a silicon drift detector is used to measure photon energy and arrival time.The measurement system consists of a signal detector,a processing unit,a signal acquisition unit and a data receiving unit.This system acquires the energy resolution and arrival time information of photons.In particular,background noise with different energies disturbs pulse profile forming,the system can also achieve a high signal-to-noise ratio profile.Ground test results show that this system can be applied in autonomous navigation based on X-ray pulsar measurement.
基金supported by the Special Funds of the National Natural Science Foundation of China (Grant No.10947017/A05)
文摘By virtue of the generalised Hermann-Feynmam theorem we re-derive the energy average formula of photon gas. This is another useful application of the theorem.
基金This work was supported by the National Natural Science Foundation of China(No.12005239).
文摘The high-energy photon source(HEPS)is the first fourth-generation synchrotron light source facility in China.The HEPS injector consists of a linear accelerator(Linac)and a full energy booster.The booster captures the electron beam from the Linac and increases its energy to the value required for the storage ring.The full-energy beam could be injected to the storage ring directly or after“high-energy accumulation.”On November 17,2023,the key booster parameters successfully reached their corresponding target values.These milestone results were achieved based on numerous contributions,including nearly a decade of physical design,years of equipment development and installation,and months of beam commissioning.As measured at the extraction energy of 6 GeV,the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm rad with a single-bunch charge of 5.58 nC,compared with the corresponding target values of 6.6 mA and 35 nm rad,respectively.This paper presents the physical design,equipment development,installation,and commissioning process of the HEPS booster.
文摘The Ionising irradiations used mostly in the treatment of tumoral diseasses are: X, γ, β and e irradiations. The discussion will be about γ irradiations, produced in linear accelerator with photon energy 6 MV and 15 MV. It is important to know the absorption performance before and after the electronic equilibrium. This is a reason that we’ve used the function of dose gradient for irradiations γ. It represents the velocity of dose change as a function of depth in tissue. From skin to maximum dose value, the increase of G-function is more accentuated for γ-rays than for β-particles while after that the G-function decreasing is less sharp for γ-rays. Finally, we’ll discuss about the advantages in terms of radiation protection of γ-rays used in radiotherapy.
文摘This paper begins by exploring a useful and neglected detail of a photon—its physical size perpendicular to the direction of propagation in the same way as an atom or neutron has a physical size. Such a photon size would be quite separate from the cross-section of a photonic interaction, which depends on the material interacting. Such a perpendicular dimension of a photon will be invariant under Lorentz transform parallel to the light propagation direction and will thus be the same for all frequencies of light. This study also leads to new details about how a photon interacts, offering an explanation for the familiar physics where light slightly above and below the mean frequency of an excited state can still excite the same state without violation of conservation of energy—a mystery explored thoroughly in a previous paper without finding the solution offered here. As usual, a better elucidation of the details of light interaction also leads to new insights—especially about the vacuum field. The <strong>Appendix </strong>summarizes some previous research relevant to this
文摘Many properties of a single photon, such as density, rest mass, and orbital angular momentum, are still unknown. In a previous study, the photon was presented as a superfluid prolate spheroid structure, with a long-axis radius, short-axis radius, and volume, embodied with two spins—transversal and longitudinal—which are responsible for the three-dimensional helical trajectory of the electromagnetic wave. In this study, the rest mass, density, and energy of photon are mathematically derived, and the relationship between the radius of photon and its frequency is demonstrated. In addition, the difference between the Compton and de Broglie wavelengths is clarified. The calculated density, volume, and rest mass of photon agree with previous experimental results. The photon’s simultaneous longitudinal and transversal spins are moving forces of longitudinal and transversal trajectories, which are the origin of the three-dimensional helix shape of the electromagnetic field. A new mechanism for the photon movement is proposed, and the reason for the zero mass moving photon is revealed;a traveling photon in space exhibits zero mass because its boundaries demonstrate zero relative velocity with the surrounding vacuum. The orbital angular momentum of photon is described using similar macroscopic rotation concepts and applying hydrodynamics laws. A rotating photon is endowed with an angular velocity vector whose magnitude measures the speed with which the radius of the principal axis sweeps an angle, and whose direction indicates the principal axis of rotation and is given by the right-hand rule. The deviation angle is calculated using trigonometric functions, and the origin of the Lorenz factor is revealed.
基金supported by High Energy Photon Source(HEPS),a major national science and technology infrastructure in China.Funding was also received from the Chinese Academy of Sciences and the National Natural Science Foundation of China(Grant No.12275285).
文摘Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to accommodate the accelerator physics design.Superconducting rf(srf)technologies were chosen for the storage ring rf accompanied by solid-state power amplifiers and digital low-level rf controls.The design of the rf system was completed,and the parameters are frozen.Elucidation of the rf design with key parameters is desired.Methods The requirements from the accelerator physics design will be presented followed by the detailed rf design.The logic behind the choice of key rf parameters is elaborated.The configuration of the entire rf system is presented.Results and conclusions The fundamental srf cavity of 166.6 MHz was designed to accelerate the ultrarelativistic electron beam.Heavy damping of higher-order modes in these cavities is required to avoid the coupled bunch instabilities.An active third harmonic srf of 499.8 MHz was adopted to realize the required rf gymnastics.Normal-conducting 5-cell cavities will be used for the booster rf.Solid-state amplifiers of 2.4 MW in total will be installed at HEPS to drive these cavities in the booster and the storage ring.A digital low-level rf system will be used to regulate rf field inside each cavity with high stabilities.The rf configuration during the commissioning and the operation scenarios are also presented.
基金supported by the High Energy Photon Source(HEPS),a major national science and technology infrastructurethe National Natural Science Foundation of China(No.11922512).
文摘Purpose The physics design of the High Energy Photon Source(HEPS)was finished after many times of iteration.Hereby,the typical equilibrium electron beam parameters corresponding to the proposed two baseline operation modes in the baseline design of HEPS are presented.Methods To compute the equilibrium parameters of the electron beam,the lattice parameters,RF parameters,and the parameters of the insertion devices(IDs)were determined first.Furthermore,it is more precise to use the full-current electron beam parameters in the estimations of the performance of the synchrotron light.Therefore,not only the single-particle dynamics but also the current-dependent collective effects need to be considered in the computations of the full-current,equilibrium parameters of the electron beam.Both analytic computations and multi-particle tracking simulations were carried out.Results The full-current,equilibrium parameters of the electron beams in the HEPS storage ring are presented in this paper.Moreover,the main beam parameters in the injector(the booster and the LINAC),corresponding to the two baseline operation modes of the storage ring,are also presented.Conclusion The typical electron beam parameters corresponding to the two baseline operation modes are given in detail in this paper.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10934010)the National Basic Research Program of China (GrantNos. 2011CB921502 and 2012CB821305)
文摘The optical conductivity of a trilayer graphene is studied using the Kubo-Greenwood formula. We calculate the real part of the diagonal optical conductivity of an ABA-stacked trilayer graphene with different Fermi energies. The optical conductivity arises from interband matrix elements of the electric current operator involving the transitions from the occupied states to the unoccupied ones. We study the dependence of the real part of the diagonal optical conductivity on the photon energy, and the role of the transitions.
文摘We combine the de Broglie Matter Wave Equation with the Heisenberg Uncertainty Principle to derive an equation for time as a wave. This happens to be the first time that these two statements have been combined in this manner to derive an equation for time. The result is astounding. Time turns out to be a minuscule blob of quantum electromagnetic energy in perpetual angular momentum. From this time equation, we derive an equation for space which turns out to also predict a string (like the string of string theory). We then combine the time equation with the space equation to derive an equation for the inverse of quantum gravity which is also surprisingly electromagnetic in nature. This last statement implies that space is multidimensional and gravity in multidimensional space is not quantized, but its inverse (which is single-dimensional) is.
基金supported by the High Energy Photon Source(HEPS),a major national science and technol-ogy infrastructurethe National Natural Science Foundation of China(No.11922512)+1 种基金Youth Inno-vation Promotion Association of Chinese Academy of Sciences(No.Y201904)Bureau of Frontier Sciences and Education of Chinese Academy of Sciences(No.QYZDJ-SSW-SLH001)
文摘Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.
基金supported by the Youth Innovation Promotion Association CAS (Nos. 2019013 and Y202005)the National Natural Science Foundation of China (No. 11975254)
文摘At the High Energy Photon Source (HEPS),a high orbital stability of typically 10% of the beam size and angular divergence must be achieved.The beam size at the insertion devices is 10μm horizontally and 1μm vertically,which implies that the beam orbit must be stabilized to the sub-micrometer level.This results in stringent tolerance and quality control requirements for the series production of beam position monitor (BPM) pickups.In this study,analytical formulas were used and CST simulations were performed to analyze the effects of the mechanical tolerances of BPM pickups on beam position measurement.The results of electromagnetic?eld simulations revealed how various mechanical errors,such as button size and location accuracy,as well as the related button capacitance,exert different in?uences on the beam position measurement.The performance of an actual BPM pickup was measured,along with an assessment of the error on the beam position measurement.Additionally,a wake?eld analysis,including an investigation of trapped resonant modes and related thermal deformation,was conducted.
基金supported by the Major International Cooperation and Exchange Program of the National Natural Science Foundation of China under Grant 61120106012
文摘We review current silicon photonic devices and their performance in connection with energy consumption.Four critical issues are identified to lower energy consumption in devices and systems: reducing the influence of the thermo-optic effect, increasing the wall-plug efficiency of lasers on silicon, optimizing energy performance of modulators, and enhancing the sensitivity of photodetectors. Major conclusions are(1) Mach–Zehnder interferometer-based devices can achieve athermal performance without any extra energy consumption while microrings do not have an efficient passive athermal solution;(2) while direct bonded III–V-based Si lasers can meet system power requirement for now, hetero-epitaxial grown III–V quantum dot lasers are competitive and may be a better option for the future;(3) resonant modulators, especially coupling modulators, are promising for low-energy consumption operation even when the power to stabilize their operation is included;(4) benefiting from high sensitivity and low cost, Ge/Si avalanche photodiode is the most promising photodetector and can be used to effectively reduce the optical link power budget. These analyses and solutions will contribute to further lowering energy consumption to meet aggressive energy demands in future systems.
基金This work was supported by the Foundation of Youth Innovation Promotion Association under contracts 2019013 and Y202005,CAS.
文摘To establish a nuclear resonant scattering beamline at the High Energy Photon Source(HEPS),it is essential to develop tools for detection and cleaning of parasitic bunches,for meeting the stringent demands on bunch purity.To this end,a novel time-correlated single-photon counting system was implemented at the electron storage ring of the Beijing Electron–Positron Collider II(BEPCII).The purity deterioration process over a week-long operation was recorded by the system.In this study,the mechanism of impurity growth was analyzed by numerical methods and validated on measurements.The agreement between the experimental results and the cal-culation was fairly good.Two main sources of parasitic bunches,pre-accelerators and the Touschek scattering were confirmed.A bunch-cleaning technique,based on a sinu-soidal signal mixed with a pseudo-square wave,was also developed and implemented,and its capability to improve the bunch purity to the level of 10–7 was experimentally demonstrated.We present the experimental setup,princi-ple,and measurement results of a system for detection and cleaning of parasitic bunches.
基金Supported by NSFC(11475202,11405187)Youth Innovation Promotion Association CAS(2015009)
文摘A new generation of storage ring-based light sources,called diffraction-limited storage rings（DLSRs）,with emittance approaching the diffraction limit for multi-keV photons by means of multi-bend achromat lattices,has attracted extensive studies worldwide.Among various DLSR proposals,the hybrid multi-bend achromat concept developed at the European Synchrotron Radiation Facility（ESRF） predicts an effective way of minimizing the emittance while keeping the required chromatic sextupole strengths to an achievable level.For the High Energy Photon Source planned to be built in Beijing,an ESRF-type lattice design consisting of 48 hybrid seven-bend achromats is proposed to reach emittance as low as 60 pm-rad with a circumference of about 1296 m.Sufficient dynamic aperture,allowing vertical on-axis injection,and moderate momentum acceptance are achieved simultaneously for a promising ring performance.
基金the National Natural Science Foundation of China(Nos.11605212,11475200,and 11675194)Youth Innovation Promotion Association CAS(No.2021012)High Energy Photon Source(HEPS),a major national science and technology infrastructure in China.
文摘The High Energy Photon Source(HEPS)is a 6 GeV diffraction-limited storage ring light source under construction.The swap-out injection is adopted with the depleted bunch recycled via high-energy accumulation in the booster.The extremely high beam energy density of the bunches with an ultra-low emittance(about 30 pm horizontally and 3 pm vertically)and high bunch charges(from 1.33 to 14.4 nC)extracted from the storage ring could cause hazardous damage to the extraction Lambertson magnet in case of extraction kicker failure.To this end,we proposed the use of a pre-kicker to spoil the bunches prior to extraction,significantly reducing the maximum beam energy density down to within a safe region while still maintaining highly efficient extractions.The main parameters of the pre-kicker are simulated and discussed.
基金funded by the Youth Innovation Promotion Association CAS(Nos.2019013 and Y202005)the National Natural Science Foundation of China(No.11975254).
文摘Purpose Based on the requirements of the High Energy Photon Source(HEPS),the key components for strip-type and button-type beam position monitors(BPMs)and feedthroughs are designed and manufactured.Method The mechanical structure of the feedthroughs is designed according to the Computer Simulation Technology(CST)simulation results.Resultsandconclusions Small batches of feedthroughs are manufactured,and the structure is optimized based on mechanical,vacuum,electromagnetic,and other characteristic test results.The performance improved significantly owing to optimization through batch product testing,and quality control-related information from several manufacturers is obtained,which provide a foundation for the development of BPMs for HEPS.
基金the National Natural Science Foundation of China （Nos.21103161, 11274142, 11474131）, the National Fund for Fostering Talents of Basic Science, China（No.J1103202） and the China Postdoctoral Science Foundation（Nos.2011M500927, 2013T60319）.
文摘The emission of coumarin 6（C-6） doped in opal polymethylmethacrylate（PMMA） photonic crystal（PC） was effectively manipulated. Meanwhile the energy transfer（ET） of C-6 in PCs, which are infiltrated with sulforho- damine B（S-B）, was influenced by the concentration of energy acceptor in solution, the size of PMMA micro- sphere（SM） and the photonic stop band（PSB）. The results should be beneficial to people to further understand the potential application of PCs in optoelectronic fields.
文摘During the last few years,active personal dosimeters have been developed and have replaced passive personal dosimeters in some external monitoring systems,frequently using silicon diode detectors.Incident photons interact with the constituents of the diode detector and produce electrons.These photon-induced electrons deposit energy in the detector＇s sensitive region and contribute to the response of diode detectors.To achieve an appropriate photon dosimetry response,the detectors are usually covered by a metallic layer with an optimum thickness.The metallic cover acts as an energy compensating shield.In this paper,a software process is performed for energy compensation.Selective data sampling based on pulse height is used to determine the photon dose equivalent.This method is applied to improve the energy response in photon dosimetry.The detector design is optimized for the response function and determination of the photon dose equivalent.Photon personal dose equivalent is determined in the energy range of 0.3-6 MeV.The error values of the calculated data for this wide energy range and measured data for ^133Ba,^137Cs,^60Co and ^241Am-Be sources respectively are up to 20%and 15%.Fairly good agreement is seen between simulation and dose values obtained from our process and specifications from several photon sources.
