A new neutron-gamma discriminator based on the support vector machine(SVM) method is proposed to improve the performance of the time-of-flight neutron spectrometer. The neutron detector is an EJ-299-33 plastic scintil...A new neutron-gamma discriminator based on the support vector machine(SVM) method is proposed to improve the performance of the time-of-flight neutron spectrometer. The neutron detector is an EJ-299-33 plastic scintillator with pulse-shape discrimination(PSD) property. The SVM algorithm is implemented in field programmable gate array(FPGA) to carry out the real-time sifting of neutrons in neutron-gamma mixed radiation fields. This study compares the ability of the pulse gradient analysis method and the SVM method. The results show that this SVM discriminator can provide a better discrimination accuracy of 99.1%. The accuracy and performance of the SVM discriminator based on FPGA have been evaluated in the experiments. It can get a figure of merit of 1.30.展开更多
To satisfy high-precision,widc-rangc,and real-time neutron flux measurement requirements by the International Thermonuclear Experimental Reactor(ITF.R),a data acquisition and control system based on fission chamber de...To satisfy high-precision,widc-rangc,and real-time neutron flux measurement requirements by the International Thermonuclear Experimental Reactor(ITF.R),a data acquisition and control system based on fission chamber detectors and fast controller technology,has been developed for neutron flux monitor in ITER Equatorial Port#7.The signal processing units which arc based on a field programmable gate array and the PXI Express platform arc designed to realize the neutron flux measurement with I ms time resolution and a fast response less than 0.2 ms,together with real-time timestamps provided by a timing hoard.The application of the wide-range algorithm allows the system to measure up to 10^10cps with a relative error of less than 5%.Furthermore,the system is managed and controlled by a software based on the Experimental Physics and Industrial Control System,compliant with COntrol.Data Access and Communication architecture.展开更多
The time evolution of the argon electron-beam plasma at intermediate pressure and low electron beam intensily was presented.By applying the amplitude modulation with the frequency of 20 Hz on the stable beam current,t...The time evolution of the argon electron-beam plasma at intermediate pressure and low electron beam intensily was presented.By applying the amplitude modulation with the frequency of 20 Hz on the stable beam current,the plasma evolution was studied.A Faraday cup was used for the measurement of the electron beam current and a single electrostatic probe was used for the measurement of the ion current.Experimental results indicated that the ion current was in phase with the electron beam current in the pressure range from 200 Pa to 3000 Pa and in the beam current range lower than 20 mA,the residual density increased approximately linearly with the maximum density in the log-log plot and the fitting coefficient was irrelative to the pressure.And then three kinds of kinetic models were developed and the simulated results given by the kinetic model,without the consideration of the excited atoms,mostly approached to the experimental results.This indicated that the effect of the excited atoms on the plasma density can be ignored at intermediate pressure and low electron beam current intensity,which can greatly simplify the kinetic model.In the end.the decrease of the plasma density when the beam current was suddenly off was studied based on the simplified model and it was found that the decease characteristic at intermediate pressure was approximate to the one at high pressure at low electron beam intensity,which was in good accordance with the experimental results.展开更多
Out-of-time-ordered correlation(OTOC)functions have been used as an indicator of quantum chaos in a lot of physical systems.In this work,we numerically demonstrate that zero temperature OTOC can detect quantum phase t...Out-of-time-ordered correlation(OTOC)functions have been used as an indicator of quantum chaos in a lot of physical systems.In this work,we numerically demonstrate that zero temperature OTOC can detect quantum phase transition in the anisotropic Dicke model.The phase diagram is given with OTOC.The finite-size effect is studied.Finally,the temperature effect is discussed.展开更多
We discuss how to generate a dynamical Dp-brane with a topology of R^(p-2)×S^(2) from N D(p-2)-branes with R^(p-2) topology with or without the presence of a constant RR(p+2)-form flux.This extends the previous w...We discuss how to generate a dynamical Dp-brane with a topology of R^(p-2)×S^(2) from N D(p-2)-branes with R^(p-2) topology with or without the presence of a constant RR(p+2)-form flux.This extends the previous work(Chen and Lu 2004 arXiv:hep-th/0405265)of generating a dynamical spherical D2 brane from N DO branes in a constant RR four-form flux to a general p.In particular,dynamically generating a higher dimensional brane from lower dimensional ones does not necessarily need the presence of a relevant RR background flux but needs excess energy,lending support to the spacetime uncertainty principle.The time evolution of the dynamical p-brane for a general p remains the same as for the p=2 case,however there is a class of spatial dependent Dp configurations when p≥3.Some of these spatial-dependent Dp brane configurations and their properties have been discussed previously which can also be obtained from the time-dependent one by euclideanizing the time.Properties of the spatial-dependent solutions and their relations to the corresponding brane-anti brane system are discussed.展开更多
Due to their low cost,big reaction cross-section with neutrons,flexibility,and convenience for long distance data transfer,plastic scintillation fibers(PSF)have been increasingly used as detectors or sensors for high-...Due to their low cost,big reaction cross-section with neutrons,flexibility,and convenience for long distance data transfer,plastic scintillation fibers(PSF)have been increasingly used as detectors or sensors for high-energy neutron radiography.In this paper,Geant4 Monte Carlo simulation tool was used to obtain some characteristics of energy and angular distributions of recoil protons in plastic scintillation fibers irradiated by fast neutrons.The plastic fiber with BCF-20 as the core and an acrylic outer cladding was used in the simulation.The results show that there is a big range of energy and angular distribution of recoil protons in energies varying inversely with the recoil angle.展开更多
In this paper,a controlled laboratory experiment to investigate the response properties of reflec-tometry to the density fluctuations is presented.The reflectometer signal is observed to be highly spatially localized ...In this paper,a controlled laboratory experiment to investigate the response properties of reflec-tometry to the density fluctuations is presented.The reflectometer signal is observed to be highly spatially localized in the plasma.The quantitative measurement has demonstrated that the signal originates about one free space wavelength of the probe•wave in front of the critical layer and this position is independent of the fluctuation wavenumber.It is also found that the sensitivity of transverse response to wavenumbers is different from that of longitudinal response.展开更多
An experiment dealing with Pauli's exclusion principle was carried out by using a glow discharge device.The main purpose of the experiment is to examine the possibility of existence of anomalous electrons by measu...An experiment dealing with Pauli's exclusion principle was carried out by using a glow discharge device.The main purpose of the experiment is to examine the possibility of existence of anomalous electrons by measuring the characteristic K X-rays of the anode atoms.The electrons in helium glow discharge collected by the metal anode will be captured to the inner shell if they are not identical with the electrons of the anode metal.The experimental results show that the properties of the electrons both in helium glow discharge and metal atom are identical.展开更多
The general dispersion of tearing modes due to the effects of electron inertia and resistivity in pair plasmas is derived analytically,and is discussed in two cases：Δ＇〉〉 1 andΔ＇〈〈 1,where Δ’ is the instabil...The general dispersion of tearing modes due to the effects of electron inertia and resistivity in pair plasmas is derived analytically,and is discussed in two cases：Δ＇〉〉 1 andΔ＇〈〈 1,where Δ’ is the instability criterion of the tearing mode.It is found that the conditions under which either resistivity or electron inertia dominates depend strongly on the limit of Δ＇considered.展开更多
The small scale density Buctuations in the interior of HT-6M Ohmic plasma have been studied by CO_(2) laser collective scattering system in deuterium discharges covering a range of neQa(chord-average density times saf...The small scale density Buctuations in the interior of HT-6M Ohmic plasma have been studied by CO_(2) laser collective scattering system in deuterium discharges covering a range of neQa(chord-average density times safety factor at the limiter)and energy confinement time.Tlie relative density fluctuation level in the interior is inversely proportional to the toroidal magnetic field and average densityt and the energy con・fineineiit time te decreases with the Huctuation level increasing in the region where te linearly increases with neqa and satisfies the Goldston scaling law.It is suggested that the niicroturbulence in the interior zone is responsible for anomalous transport in tokamaks.展开更多
The essential role of zonal flow in the L-H transition and the suppression of turbulence have been studied with a long range correlation technique using Langmuir probe arrays in EAST tokamak.Two toroidally localized p...The essential role of zonal flow in the L-H transition and the suppression of turbulence have been studied with a long range correlation technique using Langmuir probe arrays in EAST tokamak.Two toroidally localized probe arrays are used to measure the zonal flow during L-H transition and H-L back transition.The energy ratio of the low frequency zonal flow to the total drift wave turbulence is calculated.During ELM-free H mode,the energy ratio is higher than that in L mode,which reveals the important role of zonal flows in regulating turbulence amplitude in L-H transition.展开更多
A new CO2 laser dispersion interferometer has been developed in the HL-2 M tokamak to measure the electron density.In order to meet the needs of high-precision measurement,a data acquisition system with real-time sign...A new CO2 laser dispersion interferometer has been developed in the HL-2 M tokamak to measure the electron density.In order to meet the needs of high-precision measurement,a data acquisition system with real-time signal conditioning(RSC)method is proposed.It can eliminate part of the impacts of environmental factors,such as mechanical vibration,light path changes,and plasma refraction effect during experiments.In harsh environments,the system can measure the line-integrated density with a high precision of 2×10^18 m^-2 with the RSC method.The system has been tested in a recent HL-2 A experimental campaign,and the results show that the RSC method plays an important role in the plasma electron density measurement.展开更多
We use a geometric model for hadron polarization in heavy ion collisions with an emphasis on the rapidity dependence.The model is based on the model of Brodsky,Gunion,and Kuhn,as well as the Bjorken scaling model.We m...We use a geometric model for hadron polarization in heavy ion collisions with an emphasis on the rapidity dependence.The model is based on the model of Brodsky,Gunion,and Kuhn,as well as the Bjorken scaling model.We make predictions regarding the rapidity dependence of global Λ polarization in the collision energy range of 7.7-200 GeV by assuming the rapidity dependence of two parameters,κ and <ρτ>. The predictions can be tested by future beam-energy-scan experiments at the Relativistic Heavy Ion Collider of Brookhaven National Lab.展开更多
We investigate the parton distribution function(PDF)uncertainty in the measurement of the effective weak mixing angle sin2θ^(l)_(eff)at the CERN Large Hadron Collider(LHC).The PDF-induced uncertainty is large in prot...We investigate the parton distribution function(PDF)uncertainty in the measurement of the effective weak mixing angle sin2θ^(l)_(eff)at the CERN Large Hadron Collider(LHC).The PDF-induced uncertainty is large in proton-proton collisions at the LHC due to the dilution effect.The measurement of the Drell-Yan forward-backward asymmetry(ApB)at the LHC can be used to reduce the PDF uncertainty in the sin2θ^(l)_(eff)measurement.However,when including the full mass range of lepton pairs in the AFB data analysis,the correlation between the PDF updating procedure and the sin2θ^(l)_(eff) extraction leads to a sizable bias in the obtained sin2θ^(l)_(eff)value.From our studies,we find that the bias can be significantly reduced by removing Drell-Yan events with invariant mass around the Z-pole region,while most of the sensitivity in reducing the PDF uncertainty remains.Furthermore,the lepton charge asymmetry in the^boson events as a function of the rapidity of the charged leptons,A±(ηl),is known to be another observable which can be used to reduce the PDF uncertainty in the sin2θ^(l)_(eff)measurement.The constraint from A±(ηl)is complementary to that from AFB,and thus no bias affects the sin2θ^(l)_(eff)extraction.The studies are performed using the error PDF Updating Method Package(ePump),which is based on Hessian updating methods.In this article,the CT14HERA2 PDF set is used as an example.展开更多
Differential and angle-integrated cross sections for the 10B(n,α)^7 Li,10B(n,α0)^7 Li and 10B(n,α1)^7 Li^*reactions have been measured at CSNS Back-n white neutron source.Two enriched(90%)10B samples 5.0 cm in diam...Differential and angle-integrated cross sections for the 10B(n,α)^7 Li,10B(n,α0)^7 Li and 10B(n,α1)^7 Li^*reactions have been measured at CSNS Back-n white neutron source.Two enriched(90%)10B samples 5.0 cm in diameter and^85.0μg/cm^2 in thickness each with an aluminum backing were prepared,and back-to-back mounted at the sample holder.The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array(LPDA)system.The neutron energy En was determined by TOF(time-of-flight)method,and the valid a events were extracted from the En-Amplitude two-dimensional spectrum.With 15 silicon detectors,the differential cross sections of a-particles were measured from 19.2°to 160.8°.Fitted with the Legendre polynomial series,the(n,a)cross sections were obtained through integration.The absolute cross sections were normalized using the standard cross sections of the 10B(n,α)^7 Li reaction in the 0.3-0.5 MeV neutron energy region.The measurement neutron energy range for the 10B(n,α)^7 Li reaction is 1.0 eV≤En<2.5 Me V(67 energy points),and that for the 10B(n,α0)^7 Li and10B(n,α1)^7 Li^*reactions is 1.0 eV≤En<1.0 MeV(59 energy points).The present results have been analyzed by the resonance reaction mechanism and the level structure of the 11B compound system,and compared with existing measurements and evaluations.展开更多
People have long begun considering the relativity of the atmospheric radioactivity with the sun activity and the atmospheric conditions.An annular eclipse of the sun took place in China on the 23rd September, 1987. On...People have long begun considering the relativity of the atmospheric radioactivity with the sun activity and the atmospheric conditions.An annular eclipse of the sun took place in China on the 23rd September, 1987. On this occasion, we performed an experimental observation of the γ-rays from 100 keV to 830 keV in atmosphere at sea level at Tianchang County in Anhui Province which is located at the southern edge of the annular eclipse band, i. e. at longitude 119°01′E, latitude 30°41′N, at an altitude of 20.8 m. The exact time of the annulr eclipse of the展开更多
Pulsed KrF lasers of two different durations (30 ns, 500 fs) are used to deposit DLCfilms. By optical emission spectroscopy and ion probe, the composite species of laser generated plas-ma plume are identified, the ave...Pulsed KrF lasers of two different durations (30 ns, 500 fs) are used to deposit DLCfilms. By optical emission spectroscopy and ion probe, the composite species of laser generated plas-ma plume are identified, the average kinetic energy of ions, the plume flux and their variation with laserenergy density, and the distance from the target are investigated. The relation of the properties of de-posited films with the plasma characteristics is studied.展开更多
Granular diamond single crystal is an outstanding material. It has many excellent physical and chemical properties, such as extreme hardness, chemical inertness, high thermal conductivity, low electrical conductivity ...Granular diamond single crystal is an outstanding material. It has many excellent physical and chemical properties, such as extreme hardness, chemical inertness, high thermal conductivity, low electrical conductivity and optical transparency. But further application of granular diamond is limited by its shape. In recent years, diamond film has attracted great attention as a functional material with the development of low-pressure synthesis technology. Compared with the granular diamond, the application prospects of diamond films in the field of electronics technology and acoustics are broader. Now the main technology to prepare diamond films is the low-pressure chemical vapor deposition (CVD)展开更多
In the recent decade, vapor synthesis of the diamond film has made great ad-vances. The diamond films have been at the initial stage of large-scale application,but the growth mechanism and relationship between the fil...In the recent decade, vapor synthesis of the diamond film has made great ad-vances. The diamond films have been at the initial stage of large-scale application,but the growth mechanism and relationship between the film structure and synthesisconditions have not been fully understood. Though diamond films can be synthesizedon many kinds of substrates, they adhere to substrates very weakly under some condi-tions. Therefore, it is important to investigate the interface state between展开更多
1 Introduction In 1980, L. W. Alvarez suggested a hypothesis that the falling of a largeextraterrestrial body upon the earth caused the extinction event at the end of theCretaceous, according to the extraordinarily hi...1 Introduction In 1980, L. W. Alvarez suggested a hypothesis that the falling of a largeextraterrestrial body upon the earth caused the extinction event at the end of theCretaceous, according to the extraordinarily high concentration of Ir in K/T boundarydeposits. Since then, studies have indicated that the iridium anomaly distributeswidely in the sections of this age over the world. However, these studies focused onthe abundance of Ir. Little attention was paid to other platinum group metals (PGM).Analyzing the abundance of Ru in boundary samples is very difficult because of展开更多
基金partially supported by the National Science and Technology Major Project of Ministry of Science and Technology of China (Grant Nos. 2014GB109003 and 2015GB111002)National Natural Science Foundation of China (Grant Nos. 11375195, 11575184, 11375004 and 11775068)
文摘A new neutron-gamma discriminator based on the support vector machine(SVM) method is proposed to improve the performance of the time-of-flight neutron spectrometer. The neutron detector is an EJ-299-33 plastic scintillator with pulse-shape discrimination(PSD) property. The SVM algorithm is implemented in field programmable gate array(FPGA) to carry out the real-time sifting of neutrons in neutron-gamma mixed radiation fields. This study compares the ability of the pulse gradient analysis method and the SVM method. The results show that this SVM discriminator can provide a better discrimination accuracy of 99.1%. The accuracy and performance of the SVM discriminator based on FPGA have been evaluated in the experiments. It can get a figure of merit of 1.30.
文摘To satisfy high-precision,widc-rangc,and real-time neutron flux measurement requirements by the International Thermonuclear Experimental Reactor(ITF.R),a data acquisition and control system based on fission chamber detectors and fast controller technology,has been developed for neutron flux monitor in ITER Equatorial Port#7.The signal processing units which arc based on a field programmable gate array and the PXI Express platform arc designed to realize the neutron flux measurement with I ms time resolution and a fast response less than 0.2 ms,together with real-time timestamps provided by a timing hoard.The application of the wide-range algorithm allows the system to measure up to 10^10cps with a relative error of less than 5%.Furthermore,the system is managed and controlled by a software based on the Experimental Physics and Industrial Control System,compliant with COntrol.Data Access and Communication architecture.
文摘The time evolution of the argon electron-beam plasma at intermediate pressure and low electron beam intensily was presented.By applying the amplitude modulation with the frequency of 20 Hz on the stable beam current,the plasma evolution was studied.A Faraday cup was used for the measurement of the electron beam current and a single electrostatic probe was used for the measurement of the ion current.Experimental results indicated that the ion current was in phase with the electron beam current in the pressure range from 200 Pa to 3000 Pa and in the beam current range lower than 20 mA,the residual density increased approximately linearly with the maximum density in the log-log plot and the fitting coefficient was irrelative to the pressure.And then three kinds of kinetic models were developed and the simulated results given by the kinetic model,without the consideration of the excited atoms,mostly approached to the experimental results.This indicated that the effect of the excited atoms on the plasma density can be ignored at intermediate pressure and low electron beam current intensity,which can greatly simplify the kinetic model.In the end.the decrease of the plasma density when the beam current was suddenly off was studied based on the simplified model and it was found that the decease characteristic at intermediate pressure was approximate to the one at high pressure at low electron beam intensity,which was in good accordance with the experimental results.
文摘Out-of-time-ordered correlation(OTOC)functions have been used as an indicator of quantum chaos in a lot of physical systems.In this work,we numerically demonstrate that zero temperature OTOC can detect quantum phase transition in the anisotropic Dicke model.The phase diagram is given with OTOC.The finite-size effect is studied.Finally,the temperature effect is discussed.
基金The author would like to thank J X Lu for fruitful discussion and acknowledge support by a grant from the NNSF of China with Grant No:11775212.
文摘We discuss how to generate a dynamical Dp-brane with a topology of R^(p-2)×S^(2) from N D(p-2)-branes with R^(p-2) topology with or without the presence of a constant RR(p+2)-form flux.This extends the previous work(Chen and Lu 2004 arXiv:hep-th/0405265)of generating a dynamical spherical D2 brane from N DO branes in a constant RR four-form flux to a general p.In particular,dynamically generating a higher dimensional brane from lower dimensional ones does not necessarily need the presence of a relevant RR background flux but needs excess energy,lending support to the spacetime uncertainty principle.The time evolution of the dynamical p-brane for a general p remains the same as for the p=2 case,however there is a class of spatial dependent Dp configurations when p≥3.Some of these spatial-dependent Dp brane configurations and their properties have been discussed previously which can also be obtained from the time-dependent one by euclideanizing the time.Properties of the spatial-dependent solutions and their relations to the corresponding brane-anti brane system are discussed.
基金Supported by National Natural Science Foundation of China(Grant No.60602065)
文摘Due to their low cost,big reaction cross-section with neutrons,flexibility,and convenience for long distance data transfer,plastic scintillation fibers(PSF)have been increasingly used as detectors or sensors for high-energy neutron radiography.In this paper,Geant4 Monte Carlo simulation tool was used to obtain some characteristics of energy and angular distributions of recoil protons in plastic scintillation fibers irradiated by fast neutrons.The plastic fiber with BCF-20 as the core and an acrylic outer cladding was used in the simulation.The results show that there is a big range of energy and angular distribution of recoil protons in energies varying inversely with the recoil angle.
基金Supported by the National Natural Science Foundation of Chinathe Doctoral Training Foundation of National Education Commission and Chinese Academy of Sciences.
文摘In this paper,a controlled laboratory experiment to investigate the response properties of reflec-tometry to the density fluctuations is presented.The reflectometer signal is observed to be highly spatially localized in the plasma.The quantitative measurement has demonstrated that the signal originates about one free space wavelength of the probe•wave in front of the critical layer and this position is independent of the fluctuation wavenumber.It is also found that the sensitivity of transverse response to wavenumbers is different from that of longitudinal response.
基金Project sapported by National Natural Science Foundation of China.
文摘An experiment dealing with Pauli's exclusion principle was carried out by using a glow discharge device.The main purpose of the experiment is to examine the possibility of existence of anomalous electrons by measuring the characteristic K X-rays of the anode atoms.The electrons in helium glow discharge collected by the metal anode will be captured to the inner shell if they are not identical with the electrons of the anode metal.The experimental results show that the properties of the electrons both in helium glow discharge and metal atom are identical.
基金supported by the National Magnetic Confinement Fusion Science ProgramNational Natural Science Foundation of China under Grant Nos.2014GB106004, 2013GB111000,11375189,11075161 and 11275260the Youth Innovation Promotion Association CAS
文摘The general dispersion of tearing modes due to the effects of electron inertia and resistivity in pair plasmas is derived analytically,and is discussed in two cases：Δ＇〉〉 1 andΔ＇〈〈 1,where Δ’ is the instability criterion of the tearing mode.It is found that the conditions under which either resistivity or electron inertia dominates depend strongly on the limit of Δ＇considered.
基金Supported by the National High Technology Program.
文摘The small scale density Buctuations in the interior of HT-6M Ohmic plasma have been studied by CO_(2) laser collective scattering system in deuterium discharges covering a range of neQa(chord-average density times safety factor at the limiter)and energy confinement time.Tlie relative density fluctuation level in the interior is inversely proportional to the toroidal magnetic field and average densityt and the energy con・fineineiit time te decreases with the Huctuation level increasing in the region where te linearly increases with neqa and satisfies the Goldston scaling law.It is suggested that the niicroturbulence in the interior zone is responsible for anomalous transport in tokamaks.
基金the EAST team for their support during the experimentssupported by the National Natural Science Foundation of China with Grant Nos.10990210,10990211,11375188,11105144,and 11375053+1 种基金the National Magnetic Confinement Fusion Science Program of China under Contracts Nos.2013GB106002, 2013GB106003the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology with Grant No.2014FXCX003
文摘The essential role of zonal flow in the L-H transition and the suppression of turbulence have been studied with a long range correlation technique using Langmuir probe arrays in EAST tokamak.Two toroidally localized probe arrays are used to measure the zonal flow during L-H transition and H-L back transition.The energy ratio of the low frequency zonal flow to the total drift wave turbulence is calculated.During ELM-free H mode,the energy ratio is higher than that in L mode,which reveals the important role of zonal flows in regulating turbulence amplitude in L-H transition.
文摘A new CO2 laser dispersion interferometer has been developed in the HL-2 M tokamak to measure the electron density.In order to meet the needs of high-precision measurement,a data acquisition system with real-time signal conditioning(RSC)method is proposed.It can eliminate part of the impacts of environmental factors,such as mechanical vibration,light path changes,and plasma refraction effect during experiments.In harsh environments,the system can measure the line-integrated density with a high precision of 2×10^18 m^-2 with the RSC method.The system has been tested in a recent HL-2 A experimental campaign,and the results show that the RSC method plays an important role in the plasma electron density measurement.
基金ZTL and QW are supported in part by the National Natural Science Foundation of China(NSFC)(11890713,11535012)JS is sup ported in part by Shandong Province Natural Science Foundation(ZR2019YQ06)。
文摘We use a geometric model for hadron polarization in heavy ion collisions with an emphasis on the rapidity dependence.The model is based on the model of Brodsky,Gunion,and Kuhn,as well as the Bjorken scaling model.We make predictions regarding the rapidity dependence of global Λ polarization in the collision energy range of 7.7-200 GeV by assuming the rapidity dependence of two parameters,κ and <ρτ>. The predictions can be tested by future beam-energy-scan experiments at the Relativistic Heavy Ion Collider of Brookhaven National Lab.
基金the National Natural Science Foundation of China(11721505,11875245)the U.S.National Science Foundation(PHY-2013791)。
文摘We investigate the parton distribution function(PDF)uncertainty in the measurement of the effective weak mixing angle sin2θ^(l)_(eff)at the CERN Large Hadron Collider(LHC).The PDF-induced uncertainty is large in proton-proton collisions at the LHC due to the dilution effect.The measurement of the Drell-Yan forward-backward asymmetry(ApB)at the LHC can be used to reduce the PDF uncertainty in the sin2θ^(l)_(eff)measurement.However,when including the full mass range of lepton pairs in the AFB data analysis,the correlation between the PDF updating procedure and the sin2θ^(l)_(eff) extraction leads to a sizable bias in the obtained sin2θ^(l)_(eff)value.From our studies,we find that the bias can be significantly reduced by removing Drell-Yan events with invariant mass around the Z-pole region,while most of the sensitivity in reducing the PDF uncertainty remains.Furthermore,the lepton charge asymmetry in the^boson events as a function of the rapidity of the charged leptons,A±(ηl),is known to be another observable which can be used to reduce the PDF uncertainty in the sin2θ^(l)_(eff)measurement.The constraint from A±(ηl)is complementary to that from AFB,and thus no bias affects the sin2θ^(l)_(eff)extraction.The studies are performed using the error PDF Updating Method Package(ePump),which is based on Hessian updating methods.In this article,the CT14HERA2 PDF set is used as an example.
基金Supported by financially the National Key R&D Program of China(2016YFA0401604)the National Natural Science Foundation of China(11775006)
文摘Differential and angle-integrated cross sections for the 10B(n,α)^7 Li,10B(n,α0)^7 Li and 10B(n,α1)^7 Li^*reactions have been measured at CSNS Back-n white neutron source.Two enriched(90%)10B samples 5.0 cm in diameter and^85.0μg/cm^2 in thickness each with an aluminum backing were prepared,and back-to-back mounted at the sample holder.The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array(LPDA)system.The neutron energy En was determined by TOF(time-of-flight)method,and the valid a events were extracted from the En-Amplitude two-dimensional spectrum.With 15 silicon detectors,the differential cross sections of a-particles were measured from 19.2°to 160.8°.Fitted with the Legendre polynomial series,the(n,a)cross sections were obtained through integration.The absolute cross sections were normalized using the standard cross sections of the 10B(n,α)^7 Li reaction in the 0.3-0.5 MeV neutron energy region.The measurement neutron energy range for the 10B(n,α)^7 Li reaction is 1.0 eV≤En<2.5 Me V(67 energy points),and that for the 10B(n,α0)^7 Li and10B(n,α1)^7 Li^*reactions is 1.0 eV≤En<1.0 MeV(59 energy points).The present results have been analyzed by the resonance reaction mechanism and the level structure of the 11B compound system,and compared with existing measurements and evaluations.
文摘People have long begun considering the relativity of the atmospheric radioactivity with the sun activity and the atmospheric conditions.An annular eclipse of the sun took place in China on the 23rd September, 1987. On this occasion, we performed an experimental observation of the γ-rays from 100 keV to 830 keV in atmosphere at sea level at Tianchang County in Anhui Province which is located at the southern edge of the annular eclipse band, i. e. at longitude 119°01′E, latitude 30°41′N, at an altitude of 20.8 m. The exact time of the annulr eclipse of the
文摘Pulsed KrF lasers of two different durations (30 ns, 500 fs) are used to deposit DLCfilms. By optical emission spectroscopy and ion probe, the composite species of laser generated plas-ma plume are identified, the average kinetic energy of ions, the plume flux and their variation with laserenergy density, and the distance from the target are investigated. The relation of the properties of de-posited films with the plasma characteristics is studied.
基金Project supported by the National Natural Science Foundation of ChinaFoundation of the Third World Academy Grant.
文摘Granular diamond single crystal is an outstanding material. It has many excellent physical and chemical properties, such as extreme hardness, chemical inertness, high thermal conductivity, low electrical conductivity and optical transparency. But further application of granular diamond is limited by its shape. In recent years, diamond film has attracted great attention as a functional material with the development of low-pressure synthesis technology. Compared with the granular diamond, the application prospects of diamond films in the field of electronics technology and acoustics are broader. Now the main technology to prepare diamond films is the low-pressure chemical vapor deposition (CVD)
基金Project supported by the National Natural Science Foundation of China.
文摘In the recent decade, vapor synthesis of the diamond film has made great ad-vances. The diamond films have been at the initial stage of large-scale application,but the growth mechanism and relationship between the film structure and synthesisconditions have not been fully understood. Though diamond films can be synthesizedon many kinds of substrates, they adhere to substrates very weakly under some condi-tions. Therefore, it is important to investigate the interface state between
文摘1 Introduction In 1980, L. W. Alvarez suggested a hypothesis that the falling of a largeextraterrestrial body upon the earth caused the extinction event at the end of theCretaceous, according to the extraordinarily high concentration of Ir in K/T boundarydeposits. Since then, studies have indicated that the iridium anomaly distributeswidely in the sections of this age over the world. However, these studies focused onthe abundance of Ir. Little attention was paid to other platinum group metals (PGM).Analyzing the abundance of Ru in boundary samples is very difficult because of
