New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scatte...New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance.Therefore,cure strategies need to be carefully studied to obtain highquality photon beams.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this study.The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations.The gains with RF frequencies of 100 MHz and 500 MHz were compared.Along with a better filling pattern,a more suitable RF frequency was adopted in the SSRF-U.The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations.Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined.The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters.Additionally,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.展开更多
In order to do alignment between the timing signal and the synchrotron X-ray pulse on the sample spot in the time domain,measuring time structure of the storage ring on the sample spot inside the experimental hutch is...In order to do alignment between the timing signal and the synchrotron X-ray pulse on the sample spot in the time domain,measuring time structure of the storage ring on the sample spot inside the experimental hutch is a foundational step during the time-resolved experiments using the pulsed synchrotron X-rays with the time structure defined by the storage ring.In this work,the method of time-resolved X-ray excited optical luminescence(TRXEOL)was designed and implemented to do the measurement.It is based on the principle of time-correlated single photon counting techniques.The measurement system consists of a spectrometer with a detector of photomultiplier tube,a timing system,a set of nuclear instrument modules and a luminescent material of zinc oxide.The measurement was performed on the X-ray absorbed fine structure spectrum beamline at Shanghai Synchrotron Radiation Facility.The results show that this method can be used to measure the time structure of the storage ring with a precision of less than 1 ns.The measurement system can also be used for the time-resolved research for the optical luminescent materials.展开更多
Characteristics of road landscaping were analyzed,as a kind of "linear" landscaping,it could be classified into urban street landscaping,urban ring road and expressway landscaping.Differences between road la...Characteristics of road landscaping were analyzed,as a kind of "linear" landscaping,it could be classified into urban street landscaping,urban ring road and expressway landscaping.Differences between road landscaping projects and other garden landscaping projects or construction projects were analyzed.Landscaping project for the South 3rd Ring Road of Xi'an City(in Yanta District)was taken for an example to summarize construction experience,discuss present conditions and features of garden landscaping supervision in China.The artistic and physiological properties of garden landscaping,as well as the supervision during maintenance period were stressed,but it was also pointed out that garden landscaping supervision in China was actually not given sufficient attention.On this basis,key points in the supervision of road landscaping project were proposed:understanding design ideas,selection of landscape plants,quality control of concealed works,prevention and control of diseases and insects,construction safety management and overall image;only by effectively implementing these key points,a high-quality road landscaping project could be realized to improve the image of a city and beautify its environment.展开更多
基金The authors would like to thank Dr.Na Wang and Sai-Ke Tian in IHEP for their useful discussions.
文摘New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance.Therefore,cure strategies need to be carefully studied to obtain highquality photon beams.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this study.The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations.The gains with RF frequencies of 100 MHz and 500 MHz were compared.Along with a better filling pattern,a more suitable RF frequency was adopted in the SSRF-U.The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations.Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined.The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters.Additionally,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.
文摘In order to do alignment between the timing signal and the synchrotron X-ray pulse on the sample spot in the time domain,measuring time structure of the storage ring on the sample spot inside the experimental hutch is a foundational step during the time-resolved experiments using the pulsed synchrotron X-rays with the time structure defined by the storage ring.In this work,the method of time-resolved X-ray excited optical luminescence(TRXEOL)was designed and implemented to do the measurement.It is based on the principle of time-correlated single photon counting techniques.The measurement system consists of a spectrometer with a detector of photomultiplier tube,a timing system,a set of nuclear instrument modules and a luminescent material of zinc oxide.The measurement was performed on the X-ray absorbed fine structure spectrum beamline at Shanghai Synchrotron Radiation Facility.The results show that this method can be used to measure the time structure of the storage ring with a precision of less than 1 ns.The measurement system can also be used for the time-resolved research for the optical luminescent materials.
文摘Characteristics of road landscaping were analyzed,as a kind of "linear" landscaping,it could be classified into urban street landscaping,urban ring road and expressway landscaping.Differences between road landscaping projects and other garden landscaping projects or construction projects were analyzed.Landscaping project for the South 3rd Ring Road of Xi'an City(in Yanta District)was taken for an example to summarize construction experience,discuss present conditions and features of garden landscaping supervision in China.The artistic and physiological properties of garden landscaping,as well as the supervision during maintenance period were stressed,but it was also pointed out that garden landscaping supervision in China was actually not given sufficient attention.On this basis,key points in the supervision of road landscaping project were proposed:understanding design ideas,selection of landscape plants,quality control of concealed works,prevention and control of diseases and insects,construction safety management and overall image;only by effectively implementing these key points,a high-quality road landscaping project could be realized to improve the image of a city and beautify its environment.
