By taking the BUU model, we simulate the superheavy element synthesis reaction. With the rotation effect being included in the BUU model, the effect of the non-centrality of the reaction ^48Ca+^238U→^286 112 is stud...By taking the BUU model, we simulate the superheavy element synthesis reaction. With the rotation effect being included in the BUU model, the effect of the non-centrality of the reaction ^48Ca+^238U→^286 112 is studied. It is shown that the promising impact parameter in the synthesis process can be released from zero to a value little smaller than the radius of the smaller nucleus involved in the reaction. Meanwhile, the compound nucleus may involve rich shape phases.展开更多
This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measu...This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.展开更多
A study of the fragments of DNA irradiated with MeV ions is important for the understanding of the DNA damage mechanism and the subsequent biological effects (induced by heavy ions). In this experiment, the products o...A study of the fragments of DNA irradiated with MeV ions is important for the understanding of the DNA damage mechanism and the subsequent biological effects (induced by heavy ions). In this experiment, the products of calf thymus DNA (CT DNA) irradiated with MeV fluorine ions were analyzed using agarose gel electrophoresis, modified time-of-flight mass spectrometer (MALDI-TOF), and high-performance liquid chromatography (HPLC). The results showed that the molecular mass of the fragments were concentrated around 831 bp with agarose gel elec- trophoresis, there was no observable product in the range of 1,000 ? 30,000 (m/q) using MALDI-TOF, and small bio- molecules were separated from the products. The results of this study indicated that the strand breaks of calf thymus DNA induced by MeV fluorine ions were nonrandom.展开更多
The diffusion behaviour of 1.0 and 2.0MeV Au^(+)implanted into LiB_(3)O_(5)single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions.Annealing was performed at temperatures of 600,700,and 800...The diffusion behaviour of 1.0 and 2.0MeV Au^(+)implanted into LiB_(3)O_(5)single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions.Annealing was performed at temperatures of 600,700,and 800℃each for 30 min.The results show that the diffusion behaviour is quite different in two cases.In LiB_(3)O_(5),the depth distribution of the 1.0MeV Au is nearly Gaussian and becomes bimodal after annealing at 800℃for 30 min.But in the case of 2.0 MeV,the depth distribution of as implanted Au^(+)in LiB_(3)O_(5)has splitting behaviour.After 800℃for 30 min annealing,there is no obvious diffusion observed.The precise interpretation is needed.展开更多
The γ-ray energy (Eγ) spectra of the superdeformed (SD) bands of odd-A nuclei in the A- 190 mass region are investigated systematically. It is found that a △1 = 4 bifurcation exists in the SD bands. Within the supe...The γ-ray energy (Eγ) spectra of the superdeformed (SD) bands of odd-A nuclei in the A- 190 mass region are investigated systematically. It is found that a △1 = 4 bifurcation exists in the SD bands. Within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry, the Eγ spectra, dynamical moments of inertia and Eγ differences δ4Eγ(I) of these bands are evaluated. Quantitative good results are obtained which show that the scheme is powerful to describe the △I = 4 bifurcation. The △I = 4 bifurcation may then come from the perturbation holding the SO(5) (or SU(5)) symmetry on the rotation. From a microscopic point of view, the △I = 4 bifurcation may be a result of the combination of theβ-phonon, γ-phonon and the rotation.展开更多
The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser (PKU-FEL) facility is carried out. In order to minimize the scale of the cryogenic system and the running ...The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser (PKU-FEL) facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities.展开更多
We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B(GT) and branching ratios of the/3 decays in ^18 N ...We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B(GT) and branching ratios of the/3 decays in ^18 N are calculated in the psd and spsdpf shell spaces with the WBT interaction. The calculations in the two different spaces are compared. The psd calculations obtain a better agreement with the observation of the β-delayed neutron emission, which seems to show that the observed properties of ^18 N and ^18 O are mainly produced by one particle being excited from the p-shell to the sd-shell.展开更多
With the Munczek-Nemirovsky model of the effective gluon propagator in the global colour model, we study the radially excited solitons in which one quark is excited and the other two are at the ground state. The obtai...With the Munczek-Nemirovsky model of the effective gluon propagator in the global colour model, we study the radially excited solitons in which one quark is excited and the other two are at the ground state. The obtained masses of the two radial excitations are comparable with the experimental data.展开更多
Bunch lengthening phenomenon is resulted from one of the most severe single bunch instabilities in storage rings. We develop a new code to calculate the single bunch length and energy spread in storage rings using FOR...Bunch lengthening phenomenon is resulted from one of the most severe single bunch instabilities in storage rings. We develop a new code to calculate the single bunch length and energy spread in storage rings using FORTRAN. In this code, wake field is calculated using an analytical formula, which is different from the previous ones. The bunch length and energy spread under different bunch currents are calculated for BEPCII by using this code, and the tracking results are in good agreement with those from other codes. The calculated energy spread clearly shows that the longitudinal microwave instability threshold is around 65 mA for BEPCII storage ring.展开更多
The International Linear Collider (ILC), which is based on super-conducting RF acceleration technology, requires the damping rings to provide beams with extremely small equilibrium emittance, and large acceptance to...The International Linear Collider (ILC), which is based on super-conducting RF acceleration technology, requires the damping rings to provide beams with extremely small equilibrium emittance, and large acceptance to ensure good injection efficiency for high-emittance, and high-energy spread beam from the positron source. In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed with modified FODO arc cells, and the total quadrupole number has been reduced by half. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. This new lattice has been optimized to have a good dynamic aperture. This alternative ILC damping ring lattice design will reduce the cost largely as compared with the baseline design.展开更多
Theω-andρ-meson tensor couplings to nucleons in a derivative scalar coupling model for finite nuclei are investigated.The influences of the tensor couplings on the binding energies per nucleon,the root-mean-square c...Theω-andρ-meson tensor couplings to nucleons in a derivative scalar coupling model for finite nuclei are investigated.The influences of the tensor couplings on the binding energies per nucleon,the root-mean-square charge radii,spin-orbit splittings and single particle energies are discussed.The obtained results show that the spin-orbit splittings for finite nuclei are more sensitive to theω-meson tensor coupling.展开更多
A planar optical waveguide is formed in monoclinic double rare-earth-tungstate laser crystal Yb:KLu(WO4)2 by 6.0 Me V oxygen ion implantation with a dose of 2 × 10^16 ions/cm^2 at room temperature. Subsequentl...A planar optical waveguide is formed in monoclinic double rare-earth-tungstate laser crystal Yb:KLu(WO4)2 by 6.0 Me V oxygen ion implantation with a dose of 2 × 10^16 ions/cm^2 at room temperature. Subsequently, annealing at 300℃ for an hour in air is performed on the sample to decrease colour centres to improve the thermal stability of the waveguide. The refractive index profiles of the waveguide are reconstructed by an effective refractive index method. Dark modes of the waveguide are observed at wavelengths of 633 nm and 1539 nm. TRIM'98 is used to simulate the damage profile caused by the implantation process. It is found that the refractive index change may be mainly due to the damage induced by the nuclear energy loss.展开更多
The optical waveguide was formed on an LiNbO_(3) substrate by 2.6 MeV nickel ions implantation to the dose of 9×10^(14) ions/cm^(2).Five dark modes were observed by the prism coupling technique.The refractive ind...The optical waveguide was formed on an LiNbO_(3) substrate by 2.6 MeV nickel ions implantation to the dose of 9×10^(14) ions/cm^(2).Five dark modes were observed by the prism coupling technique.The refractive index profile was obtained by using the reflectivity calculation method.A large index decrease was found in the guiding region and in the optical barrier,which is somewhat different from that of the LiNbO_(3) waveguide formed by the MeV He+ions.The position of the optical barrier is deeper than that of the damage peak calculated by TRIM'90(Transport of Ions in Matter)code.The crystal lattice damage in the guiding region caused by the Ni+ion implantation was analysed by the Rutherford backscattering/channelling technique.展开更多
Antikaon condensation and kaon and antikaon production in protoneutron stars are investigated in a chiral hadronic model (also referred to as the FST model in this paper). The effects of neutrino trapping on protone...Antikaon condensation and kaon and antikaon production in protoneutron stars are investigated in a chiral hadronic model (also referred to as the FST model in this paper). The effects of neutrino trapping on protoneutron stars are analyzed systematically. It is shown that neutrino trapping makes the critical density of K^- condensation delay to higher density and fifo condensation not occur. The equation of state (EOS) of (proto)neutron star matter with neutrino trapping is stiffer than that without neutrino trapping. As a result, the maximum masses of (proto)neutron stars with neutrino trapping are larger than those without neutrino trapping. If hyperons are taken into account, antikaon does not form a condensate in (proto)neutron stars. Meanwhile, the corresponding EOS becomes much softer, and the maximum masses of (proto)neutron stars are smaller than those without hyprons. Finally, our results illustrate that the Q values for K^+ and K^- production in (proto)neutron stars are not sensitive to neutrino trapping and inclusion of hyperons.展开更多
Deconlinement phase transition and neutrino trapping in (proto)neutron star matter are investigated in a chiral hadronic model (also referred to as the FST model) for the hadronic phase (HP) and in the color-fla...Deconlinement phase transition and neutrino trapping in (proto)neutron star matter are investigated in a chiral hadronic model (also referred to as the FST model) for the hadronic phase (HP) and in the color-flavor-locked (CFL) quark model for the deconlined quark phase. We include a perturbative QCD correction parameter αs in the CFL quark matter equation of states. It is shown that the CFL quark core with K^0 condensation forms in neutron star matter with the large value of αs. If the small value of αs is taken, hyperons suppress the CFL quark phase and the liP is dominant in the high-density region of (proto)neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter as or decreasing the bag constant B and the strange quark mass ms can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of (proto)neutron stars are not sensitive to the QCD correction parameter αs.展开更多
We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are inv...We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM'98 (transport of ions in matter) is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation.展开更多
A planar optical waveguide was formed in RbTiOP04 crystal by 6.0-MeV oxygen ion implantation with the dose of 2 × 10^15 ions/cm2 at room temperature. Annealing at 200℃ for 30min in air is performed to improve th...A planar optical waveguide was formed in RbTiOP04 crystal by 6.0-MeV oxygen ion implantation with the dose of 2 × 10^15 ions/cm2 at room temperature. Annealing at 200℃ for 30min in air is performed to improve the thermal stability of the waveguide. The dark modes of the waveguide are measured at wavelengths 633 and 1539 nm, respectively. The refractive index profiles in the guiding layer are reconstructed by using the reflectivity calculation method. TRIM'98 code was carried out to simulate the damage profiles caused by the implantation process to obtain a better understanding of the waveguide formation.展开更多
By taking the particle triaxial-rotor model with variable moment of inertia, we investigate the energy spectra, the deformation and the single particle configuration of the negative-parity states in nuclei^(191,193,1...By taking the particle triaxial-rotor model with variable moment of inertia, we investigate the energy spectra, the deformation and the single particle configuration of the negative-parity states in nuclei^(191,193,194,197) Au systemically. The calculated energy spectra agree well with experimental data. The obtained results indicate that the negative-parity states in^(191,193,195,197)Au originate from the proton-hole h11/2 configuration coupled to a triaxial oblate Hg core. Meanwhile the main single particle configuration of the bands 1, 2 and 3 are identified to be [5h11/2 1/2) (α=-1/2), [5h11/2 1/2) (α = 1/2) and 15h9/2 7/2), respectively.展开更多
Co-rich seamount crusts have been shown to possess great potential for providing information on paleoceanographic and paleoclimatic changes. High resolution data are essential to decipher and correctly understand such...Co-rich seamount crusts have been shown to possess great potential for providing information on paleoceanographic and paleoclimatic changes. High resolution data are essential to decipher and correctly understand such high-density records. With the development of modern microprobe techniques, detailed sampling of crusts can be performed and it is possible to retrieve detailed information about envi- ronmental changes recorded in the seamount crusts. We report here geochemical results of more than 40 elements (including all rare earth elements) of four Co-rich seamount crust samples, which were collected from seamounts in the central and western Pacific Ocean. These data were obtained with two micro-probe techniques: Electron Probe Micro Analyzer and Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The chronological framework of the seamount crust samples was determined using the cos- mogenic 10Be and the Co-chronometer. Records of elemental composition, P, and Al/(Fe + Mn) and Y/Ho ratios across the sections of the four samples are used to identify paleoceanographic and paleoclimatic events over the past ~30 Ma. These data show that: (1) Al/(Fe + Mn) in the western Pacific seamount crust is a useful proxy for the assessment of changes of source materials related to the variability of the Asian monsoon; (2) P and Y/Ho can be used as proxies to infer biogenic episodes. Finally we discuss the methodology related to dating and micro-probe analysis used in crust study.展开更多
A new linear accelerator system,called the SSC-Linac injector,is being designed at HIRFL (the heavy ion research facility of Lanzhou).As part of the SSC-Linac,the medium energy beam transport (MEBT) consists of se...A new linear accelerator system,called the SSC-Linac injector,is being designed at HIRFL (the heavy ion research facility of Lanzhou).As part of the SSC-Linac,the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles,a re-buncher and a diagnose box.The total length of this segment is about 1.75 m.The beam dynamics simulation in MEBT has been studied using the TRACK 3D particle-in-cell code,and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces,and that most of the particles can be captured by the final sector focusing cyclotron for further acceleration.The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail,and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10425521, 10075002, and 10135030, the Major State Basic Research Development Programme under Grant No G2000077400, and Doctoral Program Foundation of the Ministry of Education of China under Grant No 20040001010, the Foundation for University Key Teacher by the Ministry of Education of China.
文摘By taking the BUU model, we simulate the superheavy element synthesis reaction. With the rotation effect being included in the BUU model, the effect of the non-centrality of the reaction ^48Ca+^238U→^286 112 is studied. It is shown that the promising impact parameter in the synthesis process can be released from zero to a value little smaller than the radius of the smaller nucleus involved in the reaction. Meanwhile, the compound nucleus may involve rich shape phases.
文摘This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.
文摘A study of the fragments of DNA irradiated with MeV ions is important for the understanding of the DNA damage mechanism and the subsequent biological effects (induced by heavy ions). In this experiment, the products of calf thymus DNA (CT DNA) irradiated with MeV fluorine ions were analyzed using agarose gel electrophoresis, modified time-of-flight mass spectrometer (MALDI-TOF), and high-performance liquid chromatography (HPLC). The results showed that the molecular mass of the fragments were concentrated around 831 bp with agarose gel elec- trophoresis, there was no observable product in the range of 1,000 ? 30,000 (m/q) using MALDI-TOF, and small bio- molecules were separated from the products. The results of this study indicated that the strand breaks of calf thymus DNA induced by MeV fluorine ions were nonrandom.
基金Supported by the National Natural Science Foundation of China under Grant No.19775031,the Hong Kong University of Science and Technology Research Infracture Grant R191/92SC05Laboratory of Heavy Ion Physics,Peking University。
文摘The diffusion behaviour of 1.0 and 2.0MeV Au^(+)implanted into LiB_(3)O_(5)single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions.Annealing was performed at temperatures of 600,700,and 800℃each for 30 min.The results show that the diffusion behaviour is quite different in two cases.In LiB_(3)O_(5),the depth distribution of the 1.0MeV Au is nearly Gaussian and becomes bimodal after annealing at 800℃for 30 min.But in the case of 2.0 MeV,the depth distribution of as implanted Au^(+)in LiB_(3)O_(5)has splitting behaviour.After 800℃for 30 min annealing,there is no obvious diffusion observed.The precise interpretation is needed.
基金Supported by the National Natural Science Foundation of China under Grant No.19875001the Foundation for University Key Teacher by the Ministry of Education of China。
文摘The γ-ray energy (Eγ) spectra of the superdeformed (SD) bands of odd-A nuclei in the A- 190 mass region are investigated systematically. It is found that a △1 = 4 bifurcation exists in the SD bands. Within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry, the Eγ spectra, dynamical moments of inertia and Eγ differences δ4Eγ(I) of these bands are evaluated. Quantitative good results are obtained which show that the scheme is powerful to describe the △I = 4 bifurcation. The △I = 4 bifurcation may then come from the perturbation holding the SO(5) (or SU(5)) symmetry on the rotation. From a microscopic point of view, the △I = 4 bifurcation may be a result of the combination of theβ-phonon, γ-phonon and the rotation.
文摘The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser (PKU-FEL) facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10525520 and 10475002, the Doctoral Foundation of the Ministry of Education of China (20030001088), and the Key Project of the Ministry of Education of China under Grant No 305001.
文摘We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B(GT) and branching ratios of the/3 decays in ^18 N are calculated in the psd and spsdpf shell spaces with the WBT interaction. The calculations in the two different spaces are compared. The psd calculations obtain a better agreement with the observation of the β-delayed neutron emission, which seems to show that the observed properties of ^18 N and ^18 O are mainly produced by one particle being excited from the p-shell to the sd-shell.
基金Supported by the National Natural Science Foundation of China under contract Nos 10425521, 10575004 and 106750077 the Key Project of the Ministry of Education of China under Grant No 305001, the Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20040001010, and the Foundation for University Key Teachers by the Ministry of Education of China.
文摘With the Munczek-Nemirovsky model of the effective gluon propagator in the global colour model, we study the radially excited solitons in which one quark is excited and the other two are at the ground state. The obtained masses of the two radial excitations are comparable with the experimental data.
基金zupported by the National Natural Science Foundation of China under Grant Nos 10525525 and 10775154.
文摘Bunch lengthening phenomenon is resulted from one of the most severe single bunch instabilities in storage rings. We develop a new code to calculate the single bunch length and energy spread in storage rings using FORTRAN. In this code, wake field is calculated using an analytical formula, which is different from the previous ones. The bunch length and energy spread under different bunch currents are calculated for BEPCII by using this code, and the tracking results are in good agreement with those from other codes. The calculated energy spread clearly shows that the longitudinal microwave instability threshold is around 65 mA for BEPCII storage ring.
基金Project supported by the National Natural Science Foundation of China (Grant No 10525525). The author would like to thank Xu G., Qin Q, Jiao Y for their helpful discussions.
文摘The International Linear Collider (ILC), which is based on super-conducting RF acceleration technology, requires the damping rings to provide beams with extremely small equilibrium emittance, and large acceptance to ensure good injection efficiency for high-emittance, and high-energy spread beam from the positron source. In order to reduce the cost for ILC damping rings, an alternative lattice which is different from the baseline configuration design has been designed with modified FODO arc cells, and the total quadrupole number has been reduced by half. At the same time, to decrease the total cost involved in constructing access shafts needed to supply power, cryogenics etc. for the wigglers and other systems, the number of wiggler sections is decreased from 8 to 4, and further to 2. This new lattice has been optimized to have a good dynamic aperture. This alternative ILC damping ring lattice design will reduce the cost largely as compared with the baseline design.
基金Supported in part by the Major State Basic Research Developing Program under Grant No.G2000077400.
文摘Theω-andρ-meson tensor couplings to nucleons in a derivative scalar coupling model for finite nuclei are investigated.The influences of the tensor couplings on the binding energies per nucleon,the root-mean-square charge radii,spin-orbit splittings and single particle energies are discussed.The obtained results show that the spin-orbit splittings for finite nuclei are more sensitive to theω-meson tensor coupling.
基金Supported by the National Natural Science Foundation of China under Grant No 10475052.
文摘A planar optical waveguide is formed in monoclinic double rare-earth-tungstate laser crystal Yb:KLu(WO4)2 by 6.0 Me V oxygen ion implantation with a dose of 2 × 10^16 ions/cm^2 at room temperature. Subsequently, annealing at 300℃ for an hour in air is performed on the sample to decrease colour centres to improve the thermal stability of the waveguide. The refractive index profiles of the waveguide are reconstructed by an effective refractive index method. Dark modes of the waveguide are observed at wavelengths of 633 nm and 1539 nm. TRIM'98 is used to simulate the damage profile caused by the implantation process. It is found that the refractive index change may be mainly due to the damage induced by the nuclear energy loss.
基金Supported by the National Natural Science Foundation of China under grant No.19875032Natural Science Foundation of Shandong Province.
文摘The optical waveguide was formed on an LiNbO_(3) substrate by 2.6 MeV nickel ions implantation to the dose of 9×10^(14) ions/cm^(2).Five dark modes were observed by the prism coupling technique.The refractive index profile was obtained by using the reflectivity calculation method.A large index decrease was found in the guiding region and in the optical barrier,which is somewhat different from that of the LiNbO_(3) waveguide formed by the MeV He+ions.The position of the optical barrier is deeper than that of the damage peak calculated by TRIM'90(Transport of Ions in Matter)code.The crystal lattice damage in the guiding region caused by the Ni+ion implantation was analysed by the Rutherford backscattering/channelling technique.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10575005, 10275002, 10435080, 10425521, and 10135030, the Key Project of the Ministry of Education under Grant No. 305001, and the CAS Knowledge Innovation Project under Grant No. KJcx2-sw-No2 0ne of authors (Hua Guo) is indebted to Dr. S. Pal since we can check our numerical results by using his code, and also thank Dr. Z.W. Lin for his kind help.
文摘Antikaon condensation and kaon and antikaon production in protoneutron stars are investigated in a chiral hadronic model (also referred to as the FST model in this paper). The effects of neutrino trapping on protoneutron stars are analyzed systematically. It is shown that neutrino trapping makes the critical density of K^- condensation delay to higher density and fifo condensation not occur. The equation of state (EOS) of (proto)neutron star matter with neutrino trapping is stiffer than that without neutrino trapping. As a result, the maximum masses of (proto)neutron stars with neutrino trapping are larger than those without neutrino trapping. If hyperons are taken into account, antikaon does not form a condensate in (proto)neutron stars. Meanwhile, the corresponding EOS becomes much softer, and the maximum masses of (proto)neutron stars are smaller than those without hyprons. Finally, our results illustrate that the Q values for K^+ and K^- production in (proto)neutron stars are not sensitive to neutrino trapping and inclusion of hyperons.
基金National Natural Science Foundation of China under Grant Nos.10575005,10435080,10425521,10135030,and 10575123the Key Grant Project of the Ministry of Education under Grant No.305001the CAS Knowledge Innovation Project under Grant No.KJcx2-sw-No2
文摘Deconlinement phase transition and neutrino trapping in (proto)neutron star matter are investigated in a chiral hadronic model (also referred to as the FST model) for the hadronic phase (HP) and in the color-flavor-locked (CFL) quark model for the deconlined quark phase. We include a perturbative QCD correction parameter αs in the CFL quark matter equation of states. It is shown that the CFL quark core with K^0 condensation forms in neutron star matter with the large value of αs. If the small value of αs is taken, hyperons suppress the CFL quark phase and the liP is dominant in the high-density region of (proto)neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter as or decreasing the bag constant B and the strange quark mass ms can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of (proto)neutron stars are not sensitive to the QCD correction parameter αs.
基金Supported by the National Natural Science Foundation of China under Grant No 10505013, and the Natural Science Foundation of Shandong Province under Grant No Y2005A01.
文摘We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM'98 (transport of ions in matter) is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10475052, 10505013 and 10575067, and the Key Laboratory of Heavy Ion Fhysics of-Education Ministry (Peking University).
文摘A planar optical waveguide was formed in RbTiOP04 crystal by 6.0-MeV oxygen ion implantation with the dose of 2 × 10^15 ions/cm2 at room temperature. Annealing at 200℃ for 30min in air is performed to improve the thermal stability of the waveguide. The dark modes of the waveguide are measured at wavelengths 633 and 1539 nm, respectively. The refractive index profiles in the guiding layer are reconstructed by using the reflectivity calculation method. TRIM'98 code was carried out to simulate the damage profiles caused by the implantation process to obtain a better understanding of the waveguide formation.
基金Supported by the National Natural Science foundation with contract No 10425521, the Major State Basic Research and Development Programme of China under Grant No G2000077400, the Natural Science foundation of Guangdong Province under Grant No 04011642, and the Natural Science Research Foundation of the Education Department of Guangdong Province under Grant No Z02069.
文摘By taking the particle triaxial-rotor model with variable moment of inertia, we investigate the energy spectra, the deformation and the single particle configuration of the negative-parity states in nuclei^(191,193,194,197) Au systemically. The calculated energy spectra agree well with experimental data. The obtained results indicate that the negative-parity states in^(191,193,195,197)Au originate from the proton-hole h11/2 configuration coupled to a triaxial oblate Hg core. Meanwhile the main single particle configuration of the bands 1, 2 and 3 are identified to be [5h11/2 1/2) (α=-1/2), [5h11/2 1/2) (α = 1/2) and 15h9/2 7/2), respectively.
基金the Key Laboratory of Marine Sedimentology and Environmental Geol- ogy, State Oceanic Administration (Grant No. MASEG200602)China Ocean Mineral Resources Research and Development Association (Grant No. DY105-01-04-05)Programme of Excellent Young Scientists of the Ministry of Land and Resources
文摘Co-rich seamount crusts have been shown to possess great potential for providing information on paleoceanographic and paleoclimatic changes. High resolution data are essential to decipher and correctly understand such high-density records. With the development of modern microprobe techniques, detailed sampling of crusts can be performed and it is possible to retrieve detailed information about envi- ronmental changes recorded in the seamount crusts. We report here geochemical results of more than 40 elements (including all rare earth elements) of four Co-rich seamount crust samples, which were collected from seamounts in the central and western Pacific Ocean. These data were obtained with two micro-probe techniques: Electron Probe Micro Analyzer and Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The chronological framework of the seamount crust samples was determined using the cos- mogenic 10Be and the Co-chronometer. Records of elemental composition, P, and Al/(Fe + Mn) and Y/Ho ratios across the sections of the four samples are used to identify paleoceanographic and paleoclimatic events over the past ~30 Ma. These data show that: (1) Al/(Fe + Mn) in the western Pacific seamount crust is a useful proxy for the assessment of changes of source materials related to the variability of the Asian monsoon; (2) P and Y/Ho can be used as proxies to infer biogenic episodes. Finally we discuss the methodology related to dating and micro-probe analysis used in crust study.
基金Supported by National Natural Science Foundation of China (10635090)
文摘A new linear accelerator system,called the SSC-Linac injector,is being designed at HIRFL (the heavy ion research facility of Lanzhou).As part of the SSC-Linac,the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles,a re-buncher and a diagnose box.The total length of this segment is about 1.75 m.The beam dynamics simulation in MEBT has been studied using the TRACK 3D particle-in-cell code,and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces,and that most of the particles can be captured by the final sector focusing cyclotron for further acceleration.The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail,and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original design.